Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2017 shares
Document And Entity Information [Abstract]
Entity Registrant Name	QEP RESOURCES, INC.
Entity Central Index Key	0001108827
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	240,935,039
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
REVENUES
Oil sales	$ 218.0	$ 201.6	$ 655.7	$ 553.1
Gas sales	130.7	123.2	399.4	287.5
NGL sales	32.2	19.8	84.0	56.2
Other revenue	3.6	2.5	10.3	4.3
Purchased oil and gas sales	5.6	35.3	44.5	76.3
Total Revenues	390.1	382.4	1,193.9	977.4
OPERATING EXPENSES
Purchased oil and gas expense	6.9	37.1	45.4	80.8
Lease operating expense	76.2	50.7	215.4	163.3
Transportation and processing costs	60.2	75.8	202.6	218.9
Gathering and other expense	1.7	0.9	5.0	3.8
General and administrative	43.4	66.5	108.3	157.9
Production and property taxes	28.5	26.8	86.1	65.3
Depreciation, depletion and amortization	176.9	217.8	560.2	667.5
Exploration expenses	21.3	0.2	21.7	0.9
Impairment	28.3	5.0	28.4	1,188.2
Total operating expenses	443.4	480.8	1,273.1	2,546.6
Net gain (loss) from asset sales	185.4	5.3	205.2	5.0
OPERATING INCOME (LOSS)	132.1	(93.1)	126.0	(1,564.2)
Realized and unrealized gains (losses) on derivative contracts (Note 7)	(104.3)	44.5	163.3	(85.1)
Interest and other income (expense)	0.1	4.6	2.5	5.6
Interest expense	(34.4)	(35.9)	(103.1)	(109.2)
INCOME (LOSS) BEFORE INCOME TAXES	(6.5)	(79.9)	188.7	(1,752.9)
Income tax (provision) benefit	3.2	29.0	(69.7)	641.2
NET INCOME (LOSS)	$ (3.3)	$ (50.9)	$ 119.0	$ (1,111.7)
Earnings per common share
Earnings Per Share, Basic	$ (0.01)	$ (0.21)	$ 0.49	$ (5.15)
Earnings Per Share, Diluted	$ (0.01)	$ (0.21)	$ 0.49	$ (5.15)
Weighted-average common shares outstanding
Used in basic calculation (in shares)	240.7	239.6	240.5	215.7
Used in diluted calculation (in shares)	240.7	239.6	240.5	215.7
Dividends per common share (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Statement of Comprehensive Income [Abstract]

Net income (loss)

$ (3.3)

$ (50.9)

$ 119.0

$ (1,111.7)

Postretirement medical plan change

^[1]

0.0

1.6

0.0

Pension and other postretirement plans adjustments:

Amortization of prior service costs

^[2]

0.1

0.2

0.4

0.6

Amortization of net actuarial losses

^[3]

0.1

0.2

0.4

Other comprehensive income

0.2

0.4

2.2

1.0

Comprehensive income (loss)

(3.1)

(50.5)

121.2

(1,110.7)

Postretirement medical plan changes, income tax expense

0.0

(1.0)

0.0

Amortization of prior service cost, income tax expense

(0.1)

(0.3)

(0.4)

Amortization of net actuarial loss, income tax expense

$ 0.0

$ (0.1)

$ (0.2)

[1]	Presented net of income tax expense of $1.0 million during the nine months ended September 30, 2017
[2]	Presented net of income tax expense of $0.1 million and $0.3 million during the three and nine months ended September 30, 2017, respectively. Presented net of income tax expense of $0.1 million and $0.4 million during the three and nine months ended September 30, 2016, respectively.
[3]	Presented net of income tax expense of $0.1 million during the nine months ended September 30, 2017. Presented net of income tax expense of $0.1 million and $0.2 million during the three and nine months ended September 30, 2016, respectively.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Postretirement medical plan changes, income tax expense	$ 0.0	$ 0.0	$ (1.0)	$ 0.0
Pension and other postretirement plans adjustments:
Amortization of prior service cost, income tax expense	(0.1)	(0.1)	(0.3)	(0.4)
Amortization of net actuarial loss, income tax expense	$ 0.0	$ (0.1)	$ (0.1)	$ (0.2)

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 782.6	$ 443.8
Accounts receivable, net	120.4	155.7
Income tax receivable	17.9	18.6
Fair value of derivative contracts	3.8	0.0
Hydrocarbon inventories, at lower of average cost or market	6.1	10.4
Prepaid expenses and other	10.2	11.6
Total Current Assets	941.0	640.1
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	11,847.2	14,232.5
Unproved properties	703.6	871.5
Gathering and other	311.0	301.8
Material and supplies	34.6	32.7
Total Property, Plant and Equipment	12,896.4	15,438.5
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	6,492.3	8,797.7
Gathering and other	111.9	101.8
Total Accumulated Depreciation, Depletion and Amortization	6,604.2	8,899.5
Net Property, Plant and Equipment	6,292.2	6,539.0
Fair value of derivative contracts	1.7	0.0
Other noncurrent assets	112.5	66.3
TOTAL ASSETS	7,347.4	7,245.4
Current Liabilities
Checks outstanding in excess of cash balances	0.0	12.3
Accounts payable and accrued expenses	388.6	269.7
Production and property taxes	37.4	30.1
Interest payable	32.8	32.9
Fair value of derivative contracts	13.4	169.8
Current portion of long-term debt	134.0	0.0
Total Current Liabilities	606.2	514.8
Long-term debt	1,890.6	2,020.9
Deferred income taxes	895.7	825.9
Asset retirement obligations	189.3	225.8
Fair value of derivative contracts	2.4	32.0
Other long-term liabilities	125.7	123.3
Commitments and contingencies (Note 9)
EQUITY
Common stock – par value $0.01 per share; 500.0 million shares authorized; 242.2 million and 240.7 million shares issued, respectively	2.4	2.4
Treasury stock – 1.7 million and 1.1 million shares, respectively	(33.2)	(22.9)
Additional paid-in capital	1,390.5	1,366.6
Retained earnings	2,292.3	2,173.3
Accumulated other comprehensive income (loss)	(14.5)	(16.7)
Total Shareholders' Equity	3,637.5	3,502.7
TOTAL LIABILITIES AND EQUITY	$ 7,347.4	$ 7,245.4

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2017	Dec. 31, 2016
EQUITY
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500.0	500.0
Common stock, shares issued (in shares)	242.8	240.7
Treasury stock (in shares)	1.9	1.1

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES
Net income (loss)	$ 119.0	$ (1,111.7)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	560.2	667.5
Deferred income taxes	68.5	(581.1)
Impairment	28.4	1,188.2
Bargain purchase gain from acquisition	0.4	(4.4)
Other non-cash activity	(9.4)	0.0
Dry hole exploratory well expense	21.2	0.0
Share-based compensation	13.5	29.0
Amortization of debt issuance costs and discounts	4.8	4.8
Net (gain) loss from asset sales	(205.2)	(5.0)
Unrealized (gains) losses on marketable securities	(2.1)	(1.2)
Unrealized (gains) losses on derivative contracts	(161.6)	218.6
Changes in operating assets and liabilities	44.1	128.2
Net Cash Provided by (Used in) Operating Activities	481.8	532.9
INVESTING ACTIVITIES
Property acquisitions	(94.5)	(39.9)
Acquisition deposit held in escrow	(36.6)	(30.0)
Property, plant and equipment, including dry exploratory well expense	(779.6)	(411.2)
Proceeds from disposition of assets	787.9	28.9
Net Cash Provided by (Used in) Investing Activities	(122.8)	(452.2)
FINANCING ACTIVITIES
Checks outstanding in excess of cash balances	(12.3)	(25.5)
Repayments of senior notes	0.0	(176.8)
Long-term debt issuance costs paid	(1.1)	0.0
Proceeds from credit facility	2.0	0.0
Repayments of credit facility	(2.0)	0.0
Treasury stock repurchases	(6.8)	(4.1)
Proceeds from issuance of common stock, net	0.0	781.6
Excess tax (provision) benefit on share-based compensation	0.0	0.2
Net Cash Provided by (Used in) Financing Activities	(20.2)	575.4
Change in cash and cash equivalents	338.8	656.1
Beginning cash and cash equivalents	443.8	376.1
Ending cash and cash equivalents	782.6	1,032.2
Supplemental Disclosures:
Cash paid for interest, net of capitalized interest	96.6	107.0
Cash paid (refund received) for income taxes	0.5	(123.3)
Non-cash Investing Activities
Change in capital expenditure accruals and other non-cash adjustments	$ 68.0	$ (20.4)

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation [Text Block]	Nature of Business QEP Resources, Inc. is an independent crude oil and natural gas exploration and production company focused in two regions of the United States: the Northern Region (primarily in North Dakota and Utah) and the Southern Region (primarily in Texas and Louisiana). Unless otherwise specified or the context otherwise requires, all references to "QEP" or the "Company" are to QEP Resources, Inc. and its subsidiaries on a consolidated basis. QEP's corporate headquarters are located in Denver, Colorado and shares of QEP's common stock trade on the New York Stock Exchange (NYSE) under the ticker symbol "QEP". Basis of Presentation of Interim Condensed Consolidated Financial Statements The interim Condensed Consolidated Financial Statements contain the accounts of QEP and its majority-owned or controlled subsidiaries. The Condensed Consolidated Financial Statements were prepared in accordance with Generally Accepted Accounting Principles (GAAP) in the United States and with the instructions for Quarterly Reports on Form 10-Q and Regulation S-X. All significant intercompany accounts and transactions have been eliminated in consolidation. The Condensed Consolidated Financial Statements reflect all normal recurring adjustments and accruals that are, in the opinion of management, necessary for a fair statement of financial position and results of operations for the interim periods presented. Interim Condensed Consolidated Financial Statements and the year-end balance sheet do not include all of the information and notes required by GAAP for audited annual consolidated financial statements. These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. The preparation of the Condensed Consolidated Financial Statements and Notes in conformity with GAAP requires that management make estimates and assumptions that affect revenues, expenses, assets and liabilities, and disclosure of contingent assets and liabilities. Actual results could differ from estimates. The results of operations for the three and nine months ended September 30, 2017, are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. Reclassifications Certain prior period balances on the Condensed Consolidated Statement of Operations have been reclassified to conform to the current year presentation. Such reclassifications had no effect on the Company's net income, earnings per share, cash flows or retained earnings previously reported. Impairment of Long-Lived Assets During the nine months ended September 30, 2017, QEP recorded impairment charges of $28.4 million, which was primarily related to unproved leasehold acreage in the Central Basin Platform. Refer to Note 4 – Capitalized Exploratory Well Costs for more information. During the nine months ended September 30, 2016, QEP recorded impairment charges of $1,188.2 million, of which $1,167.9 million was related to proved properties due to lower future oil and gas prices, $16.6 million was related to expiring leaseholds on unproved properties and $3.7 million was related to an impairment of goodwill. Of the $1,167.9 million impairment on proved properties, $1,164.0 million related to Pinedale properties, $3.5 million related to Other Northern properties and $0.4 million related to Other Southern properties. Income Taxes During the three months ended September 30, 2017, QEP’s combined effective federal and state income tax rate was 49.2%. The effective rate is higher than the combined federal and state statutory rate primarily due to a year-to-date adjustment to the tax provision for a permanent adjustment related to marginal well tax credits as well as a change in income between states. New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which seeks to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries, across industries and across capital markets. The revenue standard contains principles that an entity will apply to determine the measurement of revenue and timing of when it is recognized. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. In addition, new and enhanced disclosures will be required. The amendment is effective prospectively for reporting periods beginning on or after December 15, 2017, and early adoption is permitted for periods beginning on or after December 15, 2016. The two permitted transition methods under the new standard are the full retrospective method, in which case the standard would be applied to each prior reporting period presented, or the modified retrospective method, in which case the cumulative effect of applying the standard would be recognized at the date of initial application. The Company does not expect net income (loss) or cash flows to be materially impacted by the new standard, however, the Company is currently analyzing whether changes to total revenues and total expenses will be necessary to properly reflect revenue for certain pipeline gathering, transportation and gas processing agreements. The Company continues to evaluate the expected disclosure requirements, changes to relevant business practices, accounting policies and control activities as a result of the adoption of the ASU and has not yet developed estimates of the quantitative impact to the Company's Condensed Consolidated Financial Statements. The Company has selected the modified retrospective method and will adopt this guidance on the effective date of January 1, 2018. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires lessees to recognize the lease assets and lease liabilities classified as operating leases on the balance sheet and disclose key quantitative and qualitative information about leasing arrangements. The amendment will be effective for reporting periods beginning after December 15, 2018, and early adoption is permitted. The Company is currently assessing the impact of the ASU on the Company's Condensed Consolidated Financial Statements. In March 2016, the FASB issued ASU No. 2016-06, Derivatives and hedging (Topic 815): Contingent put and call options in debt instruments, which clarifies the requirements for assessing whether contingent call (put) options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. The amendment was effective prospectively for reporting periods beginning on or after December 15, 2016, and early adoption was permitted. The Company adopted this standard in the first quarter of 2017 and the adoption of this new standard did not have a material impact on the Company's Condensed Consolidated Financial Statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to employee share-based payment accounting, which includes provisions intended to simplify various aspects related to how share-based compensation payments are accounted for and presented in the financial statements. This amendment was effective prospectively for reporting periods beginning after December 15, 2016, and early adoption was permitted. The Company adopted this standard in the first quarter of 2017 and the adoption of this new standard did not have a material impact on the Company's Condensed Consolidated Financial Statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the definition of a business, which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of businesses. The amendment will be effective prospectively for reporting periods beginning after December 15, 2017, and early adoption is permitted. The Company is currently assessing the impact of the ASU on the Company's Condensed Consolidated Financial Statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the test for goodwill impairment, which eliminates the requirement to calculate implied fair value of goodwill to measure the goodwill impairment charge. The amendment will be effective prospectively for reporting periods beginning after December 15, 2019, and early adoption is permitted. The Company early adopted this standard in the first quarter of 2017 and the adoption of this new standard did not have a material impact on the Company's Condensed Consolidated Financial Statements. In March 2017, the FASB issued ASU No. 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the presentation of net periodic pension cost and net periodic postretirement benefit cost, which changes how employers of a defined benefit plan present net periodic benefit cost in the statement of operations. The amendment will be effective retrospectively for reporting periods beginning after December 15, 2017, and early adoption is permitted. The Company early adopted this standard in the first quarter of 2017 and the adoption of this new standard did not have a material impact on the Company's Condensed Consolidated Financial Statements. See Note 11 – Employee Benefits for additional information regarding the Company's pension and other postretirement plans.

Acquisitions & Divestitures

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Acquisitions & Divestitures [Text Block]

2016 Permian Basin Acquisition

In October 2016, QEP acquired oil and gas properties in the Permian Basin for an aggregate purchase price of approximately $591.0 million, subject to customary post-closing purchase price adjustments (the 2016 Permian Basin Acquisition). The 2016 Permian Basin Acquisition consisted of approximately 9,600 net acres in Martin County, Texas, which are primarily held by production from existing vertical wells. The 2016 Permian Basin Acquisition was funded with cash on hand, which included proceeds from an equity offering in June 2016.

The 2016 Permian Basin Acquisition meets the definition of a business combination under ASC 805, Business Combinations, as it includes significant proved properties. QEP allocated the cost of the 2016 Permian Basin Acquisition to assets acquired and liabilities assumed based on fair values as of the acquisition date. Revenues of $18.8 million and $38.6 million and net income of $3.5 million and $5.4 million were generated from the acquired properties during the three and nine months ended September 30, 2017, respectively, and are included in QEP's Condensed Consolidated Statements of Operations. In conjunction with the 2016 Permian Basin Acquisition, the Company recorded an $18.2 million bargain purchase gain in 2016. The acquisition resulted in a bargain purchase gain primarily as a result of an increase in future oil prices from the execution of the purchase and sale agreement to the closing date of the acquisition. During the nine months ended September 30, 2017, the Company reduced the bargain purchase gain by $0.4 million due to purchase price adjustments. The bargain purchase gain is reported on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)".

The following table presents a summary of the Company's purchase accounting entries (in millions) as of September 30, 2017:



Consideration:
Total consideration	$	591.0

Amounts recognized for fair value of assets acquired and liabilities assumed:
Proved properties	$	406.2
Unproved properties	214.2
Asset retirement obligations	(11.6		)
Bargain purchase gain	(17.8		)
Total fair value	$	591.0

The following unaudited, pro forma results of operations are provided for the three and nine months ended September 30, 2016. Pro forma results are not provided for the three and nine months ended September 30, 2017, because the 2016 Permian Basin Acquisition occurred during the fourth quarter of 2016, and therefore, the results are included in QEP's results of operations for the three and nine months ended September 30, 2017. These supplemental pro forma results of operations are provided for illustrative purposes only and may not be indicative of the actual results that would have been achieved by the acquired properties for the periods presented, or that may be achieved by such properties in the future. Future results may vary significantly from the results reflected in this pro forma financial information because of future events and transactions, as well as other factors. The pro forma information is based on QEP's condensed consolidated results of operations for the three and nine months ended September 30, 2016, the acquired properties' historical results of operations and estimates of the effect of the transaction on the combined results. The pro forma results of operations have been prepared by adjusting and quantifying the historical results of QEP to include the historical results of the acquired properties based on information provided by the seller and the impact of the preliminary purchase price allocation. The pro forma results of operations do not include any cost savings or other synergies that may result from the 2016 Permian Basin Acquisition or any estimated costs that have been or will be incurred by the Company to integrate the acquired properties.



	Three Months Ended						Nine Months Ended
	September 30, 2016						September 30, 2016
	Actual			Pro forma			Actual			Pro forma
	(in millions, except per share amounts)
Revenues	$	382.4		$	387.3		$	977.4		$	991.9
Net income (loss)	$	(50.9	)	$	(51.3	)	$	(1,111.7	)	$	(1,113.4	)
Earnings (loss) per common share
Basic	$	(0.21	)	$	(0.21	)	$	(5.15	)	$	(5.16	)
Diluted	$	(0.21	)	$	(0.21	)	$	(5.15	)	$	(5.16	)

Other Acquisitions

During the nine months ended September 30, 2017, QEP acquired various oil and gas properties, which primarily included proved and unproved leasehold acreage and additional surface acreage in the Permian Basin, for an aggregate purchase price of $94.5 million. In conjunction with these acquisitions, the Company recorded $5.3 million of goodwill. The goodwill is reported on the Condensed Consolidated Balance Sheets within "Other noncurrent assets".

During the nine months ended September 30, 2016, QEP acquired various oil and gas properties, which primarily included additional interests in QEP's operated wells and additional undeveloped leasehold acreage in the Permian and Williston basins, for an aggregate purchase price of $46.1 million, of which $39.9 million was cash and $6.2 million was non-cash related to the settlement of an accounts receivable balance. In conjunction with these acquisitions, the Company recorded $3.7 million of goodwill, which was subsequently impaired in 2016, and a $4.4 million bargain purchase gain. The bargain purchase gain is reported on the Condensed Consolidated Statement of Operations within "Interest and other income (expense)".

Pinedale Divestiture

In September 2017, QEP closed on its previously announced divestiture of its assets in Pinedale (the Pinedale Divestiture), for net cash proceeds (after purchase price adjustments) of $718.2 million, subject to post-closing purchase price adjustments, and recorded a pre-tax gain on sale of $178.8 million which was recorded within "Net gain (loss) from asset sales" on the Condensed Consolidated Statements of Operations. As part of the purchase and sale agreement, at the request of the buyer, QEP agreed to enter into derivative contracts covering a portion of Pinedale's future production. Those derivative contracts were novated to the buyer at closing. In addition, QEP agreed to reimburse the buyer for certain deficiency charges it incurs related to gas processing and NGL transportation and fractionation contracts, if any, between the effective date of the sale and December 31, 2019, in an aggregate amount not to exceed $45.0 million. The fair value of the deficiency charges was measured utilizing an internally developed cash flow model discounted at QEP's weighted average cost of debt. Given the unobservable nature of the inputs, the fair value calculation associated with the deficiency charges is considered Level 3 within the fair value hierarchy. As of September 30, 2017, the liability associated with estimated future payments for this commitment was $35.0 million, of which $28.0 million is reported on the Condensed Consolidated Balance Sheets within "Accounts payable and accrued expenses" and $7.0 million is reported on the Condensed Consolidated Balance Sheets within "Other long-term liabilities".

QEP accounted for revenues and expenses related to Pinedale, including the pre-tax gain on sale of $178.8 million, during the three and nine months ended September 30, 2017 and 2016, as income from continuing operations on the Condensed Consolidated Statements of Operations because the sale of the Pinedale assets did not cause a strategic shift for the Company and as a result, did not qualify as discontinued operations under ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. The Pinedale Divestiture did, however, represent the sale of an individually significant component. For the three and nine months ended September 30, 2017, QEP recorded net income before income taxes related to Pinedale, prior to the divestiture, of $208.2 million and $251.2 million, respectively, which both include the pre-tax gain on sale of $178.8 million. For the three and nine months ended September 30, 2016, QEP recorded net income before income taxes related to Pinedale of $19.2 million and a net loss before income taxes of $1,177.0 million, respectively. The net loss before income taxes was primarily due to an impairment on proved properties of $1,164.0 million recognized in 2016 as a result of a decrease in expected future gas prices.

As a part of the Pinedale Divestiture, QEP expects to incur restructuring costs of approximately $0.8 million, of which approximately $0.5 million is related to one-time termination benefits and approximately $0.3 million is related to the relocation of certain employees. During the three and nine months ended September 30, 2017, restructuring costs of $0.5 million were incurred related to the Pinedale Divestiture, all of which were related to one-time termination benefits and will be paid in the fourth quarter of 2017. The Company expects to incur an additional $0.3 million of restructuring costs related to the relocation of certain employees within the next twelve months. These restructuring costs were recorded within "Net gain (loss) from asset sales" on the Condensed Consolidated Statement of Operations.

Other Divestitures

In addition to the Pinedale Divestiture, during the nine months ended September 30, 2017, QEP received proceeds of $69.7 million and recorded a pre-tax gain on sale of $26.4 million, primarily related to the divestiture of certain non-core properties in the Other Northern area.

During the nine months ended September 30, 2016, QEP received proceeds of $28.9 million and recorded a pre-tax gain on sale of $5.0 million, primarily related to the divestiture of certain non-core properties in the Other Southern area.

The gains and losses were recorded within "Net gain (loss) from asset sales" on the Condensed Consolidated Statements of Operations.

Earnings Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Basic earnings per share (EPS) are computed by dividing net income by the weighted-average number of common shares outstanding during the reporting period. Diluted EPS includes the potential increase in the number of outstanding shares that could result from the exercise of in-the-money stock options. QEP’s unvested restricted share awards are included in weighted-average basic common shares outstanding because, once the shares are granted, the restricted share awards are considered issued and outstanding, the historical forfeiture rate is minimal and the restricted share awards are eligible to receive dividends.

Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents are considered participating securities and are included in the computation of earnings per share pursuant to the two-class method. The Company’s unvested restricted share awards contain non-forfeitable dividend rights and participate equally with common stock with respect to dividends issued or declared. However, the Company’s unvested restricted share awards do not have a contractual obligation to share in losses of the Company. The Company’s unexercised stock options do not contain rights to dividends. Under the two-class method, the earnings used to determine basic earnings per common share are reduced by an amount allocated to participating securities. When the Company records a net loss, none of the loss is allocated to the participating securities since the securities are not obligated to share in Company losses. Use of the two-class method has an insignificant impact on the calculation of basic and diluted earnings per common share. During the three and nine months ended September 30, 2017, there were no anti-dilutive shares. During the three and nine months ended September 30, 2016, there were anti-dilutive shares of 0.2 million and 0.1 million, respectively, not included in diluted common shares outstanding as they were anti-dilutive to QEP's net loss.

The following is a reconciliation of the components of basic and diluted shares used in the EPS calculation:



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2017	2016	2017	2016
	(in millions)
Weighted-average basic common shares outstanding	240.7	239.6	240.5	215.7
Potential number of shares issuable upon exercise of in-the-money stock options under the Long-Term Stock Incentive Plan	—	—	—	—
Average diluted common shares outstanding	240.7	239.6	240.5	215.7

Capitalized Exploratory Well Costs

9 Months Ended

Sep. 30, 2017

Capitalized Exploratory Well Costs [Line Items]

Capitalized Exploratory Well Costs [Text Block]

Net changes in capitalized exploratory well costs are presented in the table below.



	Capitalized Exploratory Well Costs
	2017
	(in millions)
Balance at January 1,	$	14.2
Additions to capitalized exploratory well costs	10.6
Reclassifications to proved properties	(3.6		)
Capitalized exploratory well costs charged to expense	(21.2		)
Balance at September 30,	$	—

Central Basin Platform exploration project. During the nine months ended September 30, 2017, QEP's exploratory well activity was related to the Central Basin Platform exploration project in the Permian Basin targeting the Woodford Formation. QEP completed a second exploratory well related to this project in the first half of 2017. During the three months ended September 30, 2017, based on the performance of the two exploratory wells that were drilled and the analysis of the ultimate economic feasibility of this exploration project, QEP determined it would no longer pursue the development of the Central Basin Platform exploration project and would seek to monetize the assets. QEP charged $21.2 million of exploratory well costs to exploration expense. In conjunction with the expensing of the exploratory well costs, QEP charged $28.3 million of the associated unproved leasehold acreage in the Central Basin Platform to impairment expense during the three months ended September 30, 2017. QEP wrote down the Central Basin Platform assets to their fair market value of $3.6 million and reclassified the assets to proved properties.

Asset Retirement Obligations

9 Months Ended

Sep. 30, 2017

Asset Retirement Obligation [Abstract]

Asset Retirement Obligations [Text Block]

QEP records asset retirement obligations (ARO) associated with the retirement of tangible, long-lived assets. The Company's ARO liability applies primarily to abandonment costs associated with oil and gas wells and certain other properties. The fair values of such costs are estimated by Company personnel based on abandonment costs of similar assets and depreciated over the life of the related assets. Revisions to the ARO estimates result from changes in expected cash flows or material changes in estimated asset retirement costs. The ARO liability is adjusted to present value each period through an accretion calculation using a credit-adjusted risk-free interest rate. Of the $194.2 million and $231.6 million ARO liability for the periods ended September 30, 2017 and December 31, 2016, respectively, $4.9 million and $5.8 million, respectively, were included as a liability within "Accounts payable and accrued expenses" on the Condensed Consolidated Balance Sheets.

The following is a reconciliation of the changes in the Company's ARO for the period specified below:



	Asset Retirement Obligations
	2017
	(in millions)
ARO liability at January 1,	$	231.6
Accretion	6.0
Additions	6.2
Revisions	0.2
Liabilities related to assets sold⁽¹⁾	(40.8		)
Liabilities settled	(9.0		)
ARO liability at September 30,	$	194.2

____________________________


⁽¹⁾	Liabilities related to assets sold for the nine months ended September 30, 2017, includes $34.9 million related to the Pinedale Divestiture (refer to Note 2 – Acquisitions and Divestitures for more information).

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements [Text Block]

QEP measures and discloses fair values in accordance with the provisions of ASC 820, Fair Value Measurements and Disclosures. This guidance defines fair value in applying GAAP, establishes a framework for measuring fair value and expands disclosures about fair value measurements. ASC 820 also establishes a fair value hierarchy. Level 1 inputs are quoted prices (unadjusted) for identical assets or liabilities in active markets that the Company has the ability to access at the measurement date. Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 3 inputs are unobservable inputs for the asset or liability.

QEP has determined that its commodity derivative instruments are Level 2. The Level 2 fair value of commodity derivative contracts (see Note 7 – Derivative Contracts) is based on market prices posted on the respective commodity exchange on the last trading day of the reporting period and industry standard discounted cash flow models. QEP primarily applies the market approach for recurring fair value measurements and maximizes its use of observable inputs and minimizes its use of unobservable inputs. QEP considers bid and ask prices for valuing the majority of its assets and liabilities measured and reported at fair value. In addition to using market data, QEP makes assumptions in valuing its assets and liabilities, including assumptions about risk and the risks inherent in the inputs to the valuation technique. The Company's policy is to recognize significant transfers between levels at the end of the reporting period.

Certain of the Company's commodity derivative instruments are valued using industry standard models that consider various inputs, including quoted forward prices for commodities, time value, volatility, and current market and contractual prices for the underlying instruments, as well as other relevant economic measures. Substantially all of these inputs are observable in the marketplace throughout the full term of the instrument and can be derived from observable data or are supported by observable prices at which transactions are executed in the marketplace. The determination of fair value for derivative assets and liabilities also incorporates nonperformance risk for counterparties and for QEP. Derivative contract fair values are reported on a net basis to the extent a legal right of offset with the counterparty exists.

The fair value of financial assets and liabilities at September 30, 2017 and December 31, 2016, is shown in the table below:



	Fair Value Measurements
	Gross Amounts of Assets and Liabilities						Netting Adjustments⁽¹⁾			Net Amounts Presented on the Condensed Consolidated Balance Sheets
	Level 1		Level 2		Level 3		Netting Adjustments⁽¹⁾
	September 30, 2017
Financial Assets	(in millions)
Fair value of derivative contracts – short-term	$	—	$	6.9	$	—	$	(3.1	)	$	3.8
Fair value of derivative contracts – long-term	—		2.5		—		(0.8		)	1.7
Total financial assets	$	—	$	9.4	$	—	$	(3.9	)	$	5.5

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	16.5	$	—	$	(3.1	)	$	13.4
Fair value of derivative contracts – long-term	—		3.2		—		(0.8		)	2.4
Total financial liabilities	$	—	$	19.7	$	—	$	(3.9	)	$	15.8

	December 31, 2016
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	—	$	—	$	—		$	—
Fair value of derivative contracts – long-term	—		—		—		—			—
Total financial assets	$	—	$	—	$	—	$	—		$	—

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	169.8	$	—	$	—		$	169.8
Fair value of derivative contracts – long-term	—		32.0		—		—			32.0
Total financial liabilities	$	—	$	201.8	$	—	$	—		$	201.8

_______________________


⁽¹⁾	The Company nets its derivative contract assets and liabilities outstanding with the same counterparty on the Condensed Consolidated Balance Sheets, for the contracts that contain netting provisions. See Note 7 – Derivative Contracts for additional information regarding the Company's derivative contracts.

The following table discloses the fair value and related carrying amount of certain financial instruments not disclosed in other Notes to the Condensed Consolidated Financial Statements in this Quarterly Report on Form 10-Q:



	Carrying Amount		Level 1 Fair Value		Carrying Amount		Level 1 Fair Value
	September 30, 2017				December 31, 2016
Financial Assets	(in millions)
Cash and cash equivalents	$	782.6	$	782.6	$	443.8	$	443.8
Financial Liabilities
Checks outstanding in excess of cash balances	$	—	$	—	$	12.3	$	12.3
Long-term debt	$	2,024.6	$	2,062.1	$	2,020.9	$	2,104.3

The carrying amounts of cash and cash equivalents and checks outstanding in excess of cash balances approximate fair value. The fair value of fixed-rate long-term debt is based on the trading levels and dollar prices for the Company’s debt at the end of the quarter.

The initial measurement of ARO at fair value is calculated using discounted cash flow techniques and is based on internal estimates of future retirement costs associated with property, plant and equipment. Significant Level 3 inputs used in the calculation of ARO includes plugging costs and reserve lives. A reconciliation of the Company’s ARO is presented in Note 5 – Asset Retirement Obligations.

Nonrecurring Fair Value Measurements

The provisions of the fair value measurement standard are also applied to the Company's nonrecurring measurements. The Company utilizes fair value on a periodic basis to review its proved oil and gas properties for potential impairment when events and circumstances indicate a possible decline in the recoverability of the carrying value of such property. During the nine months ended September 30, 2017, the Company recorded no impairments on proved oil and gas properties. During the nine months ended September 30, 2016, the Company recorded impairments on certain proved oil and gas properties of $1,167.9 million resulting in a reduction of the associated carrying value to fair value. The fair value of the property was measured utilizing the income approach and utilizing inputs that are primarily based upon internally developed cash flow models discounted at an appropriate weighted average cost of capital. Given the unobservable nature of the inputs, fair value calculations associated with proved oil and gas property impairments are considered Level 3 within the fair value hierarchy.

Acquisitions of proved and unproved properties are also measured at fair value on a nonrecurring basis. The Company utilizes a discounted cash flow model to estimate the fair value of acquired property as of the acquisition date which utilizes the following inputs to estimate future net cash flows: (i) estimated quantities of oil, gas and NGL reserves; (ii) estimates of future commodity prices; and (iii) estimated production rates, future operating and development costs, which are based on the Company's historic experience with similar properties. In some instances, market comparable information of recent transactions is used to estimate fair value of unproved acreage. Due to the unobservable characteristics of the inputs, the fair value of the acquired properties is considered Level 3 within the fair value hierarchy. See Note 2 – Acquisitions and Divestitures for additional information on the fair value of acquired properties.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Derivative Contracts

9 Months Ended

Sep. 30, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

QEP has established policies and procedures for managing commodity price volatility through the use of derivative instruments. In the normal course of business, QEP uses commodity price derivative instruments to reduce the impact of potential downward movements in commodity prices on cash flow, returns on capital investment, and other financial results. However, these instruments typically limit gains from favorable price movements. The volume of production subject to commodity derivative instruments and the mix of the instruments are frequently evaluated and adjusted by management in response to changing market conditions. QEP may enter into commodity derivative contracts for up to 100% of forecasted production, but generally, QEP enters into commodity derivative contracts for approximately 50% to 75% of its forecasted annual production by the end of the first quarter of each fiscal year. In addition, QEP may enter into commodity derivative contracts on a portion of its storage transactions. QEP does not enter into commodity derivative contracts for speculative purposes.

QEP uses commodity derivative instruments known as fixed-price swaps or collars to realize a known price or price range for a specific volume of production delivered into a regional sales point. QEP's commodity derivative instruments do not require the physical delivery of oil or gas between the parties at settlement. All transactions are settled in cash with one party paying the other for the net difference in prices, multiplied by the contract volume, for the settlement period. Oil price derivative instruments are typically structured as NYMEX fixed-price swaps based at Cushing, Oklahoma or oil price swaps that use Intercontinental Exchange, Inc. (ICE) Brent oil prices as the reference price. Gas price derivative instruments are typically structured as fixed-price swaps or collars at NYMEX Henry Hub or regional price indices. QEP also enters into oil and gas basis swaps to achieve a fixed-price swap for a portion of its oil and gas sales at prices that reference specific regional index prices.

QEP does not currently have any commodity derivative transactions that have margin requirements or collateral provisions that would require payments prior to the scheduled settlement dates. QEP's commodity derivative contract counterparties are typically financial institutions and energy trading firms with investment-grade credit ratings. QEP routinely monitors and manages its exposure to counterparty risk by requiring specific minimum credit standards for all counterparties, actively monitoring counterparties' public credit ratings and avoiding the concentration of credit exposure by transacting with multiple counterparties. The Company has master-netting agreements with some counterparties that allow the offsetting of receivables and payables in a default situation.

Derivative Contracts – Production

The following table presents QEP’s volumes and average prices for its commodity derivative swap contracts as of September 30, 2017:



Year	Index	Total Volumes	Average Swap Price per Unit
		(in millions)
Oil sales		(bbls)	($/bbl)
2017	NYMEX WTI	3.6	$	51.51
2018	NYMEX WTI	14.6	$	52.42
2019	NYMEX WTI	3.7	$	50.30
Gas sales		(MMBtu)	($/MMBtu)
2017	NYMEX HH	24.8	$	2.87
2017	IFNPCR	6.4	$	2.49
2018	NYMEX HH	105.9	$	2.99
2019	NYMEX HH	14.6	$	2.87

The following table presents QEP's volumes and average prices for its commodity derivative gas collars as of September 30, 2017:

Year

Index

Total Volumes

Average Price Floor

Average Price Ceiling

(in millions)

(MMBtu)

($/MMBtu)

2017

NYMEX HH

2.8

2.50

3.50

QEP uses oil and gas basis swaps, combined with NYMEX WTI and NYMEX HH fixed price swaps, to achieve fixed price swaps for the location at which it sells its physical production. The following table presents details of QEP's oil and gas basis swaps as of September 30, 2017:



Year	Index Less Differential	Index	Total Volumes	Weighted-Average Differential
			(in millions)
Oil sales			(bbls)	($/bbl)
2017	NYMEX WTI	Argus WTI Midland	1.1	$	(0.67	)
2018 (Full Year)	NYMEX WTI	Argus WTI Midland	7.3	$	(1.06	)
2018 (July through December)	NYMEX WTI	Argus WTI Midland	0.6	$	(0.81	)
2019	NYMEX WTI	Argus WTI Midland	2.2	$	(0.98	)
Gas sales			(MMBtu)	($/MMBtu)
2018	NYMEX HH	IFNPCR	7.3	$	(0.16	)

Derivative Contracts – Gas Storage

QEP enters into commodity derivative transactions to lock in a margin on gas volumes placed into storage. The following table presents QEP’s volumes and average prices for its storage commodity derivative swap contracts as of September 30, 2017:



Year	Type of Contract	Index	Total Volumes	Average Swap Price per Unit
			(in millions)
Gas sales			(MMBtu)	($/MMBtu)
2017	SWAP	IFNPCR	1.5	$	2.88
2018	SWAP	IFNPCR	0.4	$	3.05
Gas purchases			(MMBtu)	($/MMBtu)
2017	SWAP	IFNPCR	1.1	$	2.68

QEP Derivative Financial Statement Presentation

The following table identifies the Condensed Consolidated Balance Sheet location of QEP’s outstanding derivative contracts on a gross contract basis as opposed to the net contract basis presentation on the Condensed Consolidated Balance Sheets and the related fair values at the balance sheet dates:



		Gross asset derivative instruments fair value				Gross liability derivative instruments fair value
	Balance Sheet line item	September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016
Current:		(in millions)
Commodity	Fair value of derivative contracts	$	6.9	$	—	$	16.5	$	169.8
Long-term:
Commodity	Fair value of derivative contracts	2.5		—		3.2		32.0
Total derivative instruments		$	9.4	$	—	$	19.7	$	201.8

The effects of the change in fair value and settlement of QEP's derivative contracts recorded in "Realized and unrealized gains (losses) on derivative contracts" on the Condensed Consolidated Statements of Operations are summarized in the following table:



	Three Months Ended						Nine Months Ended
Derivative contracts not designated as cash flow hedges	September 30,						September 30,
Derivative contracts not designated as cash flow hedges	2017			2016			2017			2016
Realized gains (losses) on commodity derivative contracts	(in millions)
Production
Oil derivative contracts	$	12.1		$	19.1		$	21.6		$	79.8
Gas derivative contracts	(0.4		)	0.4			(19.7		)	50.8
Gas Storage
Gas derivative contracts	—			0.1			(0.2		)	2.9
Realized gains (losses) on commodity derivative contracts	11.7			19.6			1.7			133.5
Unrealized gains (losses) on commodity derivative contracts
Production
Oil derivative contracts	(86.1		)	(0.3		)	88.7			(135.9		)
Gas derivative contracts	—			24.8			100.5			(80.0		)
Gas Storage
Gas derivative contracts	—			0.4			2.3			(2.7		)
Unrealized gains (losses) on commodity derivative contracts	(86.1		)	24.9			191.5			(218.6		)
Total realized and unrealized gains (losses) on commodity derivative contracts related to production and storage contracts	$	(74.4	)	$	44.5		$	193.2		$	(85.1	)

Derivatives associated with the Pinedale Divestiture⁽¹⁾
Unrealized gains (losses) on commodity derivative contracts
Production
Oil derivative contracts	$	(1.3	)	$	—		$	(1.3	)	$	—
Gas derivative contracts	(23.5		)	—			(23.5		)	—
NGL derivative contracts	(5.1		)	—			(5.1		)	—
Unrealized gains (losses) on commodity derivative contracts related to the Pinedale Divestiture	$	(29.9	)	$	—		$	(29.9	)	$	—

Total realized and unrealized gains (losses) on commodity derivative contracts	$	(104.3	)	$	44.5		$	163.3		$	(85.1	)

_______________________

⁽¹⁾

The unrealized gains (losses) on commodity derivative contracts related to the Pinedale Divestiture are comprised of derivatives entered into in conjunction with the execution of the Pinedale purchase and sale agreement, which were subsequently novated to the buyer upon the closing of the sale in September 2017. Refer to Note 2 – Acquisitions and Divestitures for more information. The unrealized gains (losses) on commodity derivatives associated with the Pinedale Divestiture are offset by an equal amount recorded within "Net gain (loss) from asset sales" on the Condensed Consolidated Statements of Operations.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Debt

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Debt [Text Block]

As of the indicated dates, the principal amount of QEP’s debt consisted of the following:



	September 30, 2017			December 31, 2016
	(in millions)
Revolving Credit Facility due 2019	$	—		$	—
6.80% Senior Notes due 2018	134.0			134.0
6.80% Senior Notes due 2020	136.0			136.0
6.875% Senior Notes due 2021	625.0			625.0
5.375% Senior Notes due 2022	500.0			500.0
5.25% Senior Notes due 2023	650.0			650.0
Less: unamortized discount and unamortized debt issuance costs	(20.4		)	(24.1		)
Total principal amount of debt (including current portion)	2,024.6			2,020.9
Less: current portion of long-term debt	(134.0		)	—
Total long-term debt outstanding	$	1,890.6		$	2,020.9

Of the total debt outstanding on September 30, 2017, the 6.80% Senior Notes due April 1, 2018, the 6.80% Senior Notes due March 1, 2020 and the 6.875% Senior Notes due March 1, 2021, will mature within the next five years. In addition, the revolving credit facility matures on December 2, 2019.

Credit Facility

QEP’s revolving credit facility, which matures in December 2019, provides for loan commitments of $1.8 billion from a group of financial institutions. The credit facility provides for borrowings at short-term interest rates and contains customary covenants and restrictions. The credit agreement contains financial covenants (that are defined in the credit agreement) that limit the amount of debt the Company can incur and may limit the amount available to be drawn under the credit facility including: (i) a net funded debt to capitalization ratio that may not exceed 60%; (ii) a leverage ratio under which net funded debt may not exceed 4.25 times consolidated EBITDA (as defined in the credit agreement) for the fiscal quarters ending on and prior to December 31, 2017, 4.00 times for the quarters in fiscal year 2018, and 3.75 times thereafter and (iii) during a ratings trigger period, a present value coverage ratio which requires that the present value of the Company’s proved reserves must exceed net funded debt by 1.25 times at any time prior to January 1, 2018, and 1.50 times at any time on or after January 1, 2018. The Company is currently not subject to the present value coverage ratio. At September 30, 2017 and December 31, 2016, QEP was in compliance with the covenants under the credit agreement.

As of September 30, 2017 and December 31, 2016, QEP had no borrowings outstanding under the credit facility and had $1.0 million and $2.8 million, respectively, in letters of credit outstanding under the credit facility.

Senior Notes

As of September 30, 2017, the Company had $2,045.0 million principal amount of senior notes outstanding with maturities ranging from April 2018 to May 2023 and coupons ranging from 5.25% to 6.875%. The senior notes pay interest semi-annually, are unsecured senior obligations and rank equally with all of our other existing and future unsecured and senior obligations. QEP may redeem some or all of its senior notes at any time before their maturity at a redemption price based on a make-whole amount plus accrued and unpaid interest to the date of redemption. The indentures governing QEP’s senior notes contain customary events of default and covenants that may limit QEP’s ability to, among other things, place liens on its property or assets.

Commitment and Contingencies	9 Months Ended
Commitment and Contingencies	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitment and Contingencies [Text Block]	The Company is involved in various commercial and regulatory claims, litigation and other legal proceedings that arise in the ordinary course of its business. In each reporting period, the Company assesses these claims in an effort to determine the degree of probability and range of possible loss for potential accrual in its Condensed Consolidated Financial Statements. In accordance with ASC 450, Contingencies, an accrual is recorded for a material loss contingency when its occurrence is probable and damages are reasonably estimable based on the anticipated most likely outcome or the minimum amount within a range of possible outcomes. Legal proceedings are inherently unpredictable and unfavorable resolutions can occur. Assessing contingencies is highly subjective and requires judgment about uncertain future events. When evaluating contingencies related to legal proceedings, the Company may be unable to estimate losses due to a number of factors, including potential defenses, the procedural status of the matter in question, the presence of complex legal and/or factual issues, the ongoing discovery and/or development of information important to the matter. EPA Request for Information – In July 2015, QEP received an information request from the Environmental Protection Agency (EPA) pursuant to Section 114(a) of the Clean Air Act. The information request sought facts and data about certain tank batteries in QEP's Williston Basin operations. QEP timely responded to the information requests. In August 2016, the EPA requested a conference to review this matter; this conference has been scheduled for November 2017. While no formal federal enforcement action has been commenced in connection with the tank batteries to date, QEP anticipates that resolution of this matter will likely result in monetary penalties and require QEP to incur additional capital expenditures to correct noncompliance issues. We cannot reasonably estimate the loss or range of losses at this preliminary stage.

Share-Based Compensation

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation [Text Block]

QEP issues stock options, restricted share awards and restricted share units under its Long-Term Stock Incentive Plan (LTSIP) and awards performance share units under its Cash Incentive Plan (CIP) to certain officers, employees and non-employee directors. QEP recognizes the expense over the vesting periods for the stock options, restricted share awards, restricted share units and performance share units. There were 5.1 million shares available for future grants under the LTSIP at September 30, 2017.

Share-based compensation expense is recognized within "General and administrative" expense on the Condensed Consolidated Statements of Operations and is summarized in the table below:



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017			2016		2017			2016
	(in millions)
Stock options	$	0.5		$	0.6	$	1.7		$	1.8
Restricted share awards	5.4			6.0		18.7			18.2
Performance share units	(0.1		)	3.2		(6.9		)	8.8
Restricted share units	—			0.1		—			0.2
Total share-based compensation expense	$	5.8		$	9.9	$	13.5		$	29.0

Stock Options

QEP uses the Black-Scholes-Merton mathematical model to estimate the fair value of stock option awards at the date of grant. Fair value calculations rely upon subjective assumptions used in the mathematical model and may not be representative of future results. The Black-Scholes-Merton model is intended for calculating the value of options not traded on an exchange. The Company utilizes the "simplified" method to estimate the expected term of the stock options granted as there is limited historical exercise data available in estimating the expected term of the stock options. QEP uses a historical volatility method to estimate the fair value of stock options awards and the risk-free interest rate is based on the yield on U.S. Treasury strips with maturities similar to those of the expected term of the stock options. The stock options typically vest in equal installments over a three-year period from the grant date and are exercisable immediately upon vesting through the seventh anniversary of the grant date. To fulfill options exercised, QEP either reissues treasury stock or issues new shares.

The calculated fair value of stock options granted and major assumptions used in the model at the date of grant are listed below for the nine months ended September 30, 2017:



	Stock Option Assumptions
Weighted-average grant date fair value of awards granted during the period	$	6.44
Weighted-average risk-free interest rate	1.81		%
Weighted-average expected price volatility	43.9		%
Expected dividend yield	—		%
Expected term in years at the date of grant	4.5

Stock option transactions under the terms of the LTSIP are summarized below:



	Options Outstanding		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
			(per share)		(in years)	(in millions)
Outstanding at December 31, 2016	2,151,957		$	25.26
Granted	418,752		16.77
Forfeited	(14,172	)	15.33
Canceled	(202,260	)	27.55
Outstanding at September 30, 2017	2,354,277		$	23.62	3.75	$	—
Options Exercisable at September 30, 2017	1,551,861		$	27.90	2.73	$	—
Unvested Options at September 30, 2017	802,416		$	15.33	5.73	$	—

During the nine months ended September 30, 2017 and 2016, there were no exercises of stock options. As of September 30, 2017, $2.1 million of unrecognized compensation cost related to stock options granted under the LTSIP is expected to be recognized over a weighted-average vesting period of 2.23 years.

Restricted Share Awards

Restricted share award grants typically vest in equal installments over a three-year period from the grant date. The grant date fair value is determined based on the closing bid price of the Company's common stock on the grant date. The total fair value of restricted share awards that vested during the nine months ended September 30, 2017 and 2016 was $22.9 million and $24.2 million, respectively. The weighted-average grant date fair value of restricted share awards was $14.13 per share and $10.37 per share for the nine months ended September 30, 2017 and 2016, respectively. As of September 30, 2017, $25.2 million of unrecognized compensation cost related to restricted share awards granted under the LTSIP is expected to be recognized over a weighted-average vesting period of 2.17 years.

Transactions involving restricted share awards under the terms of the LTSIP are summarized below:



	Restricted Share Awards Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	3,208,503		$	14.32
Granted	2,123,016		14.13
Vested	(1,384,011	)	16.54
Forfeited	(240,732	)	14.71
Unvested balance at September 30, 2017	3,706,776		$	13.35

Performance Share Units

The payouts for performance share units are dependent upon the Company’s total shareholder return compared to a group of its peers over a three-year period. The awards are denominated in share units and have historically been delivered in cash. Beginning with awards granted in 2015, the Company has the option to settle earned awards in cash or shares of common stock under the Company's LTSIP; however, as of September 30, 2017, the Company expects to settle all awards in cash. These awards are classified as liabilities and are included within "Other long-term liabilities" on the Condensed Consolidated Balance Sheets. As these awards are dependent upon the Company's total shareholder return and stock price, they are remeasured at fair value at the end of each reporting period. The weighted-average grant date fair value of the performance share units was $16.90 per share and $10.16 per share for the nine months ended September 30, 2017 and 2016, respectively. As of September 30, 2017, $0.2 million of unrecognized compensation cost, which represents the unvested portion of the fair market value of performance shares granted, is expected to be recognized over a weighted-average vesting period of 2.03 years.

Transactions involving performance share units under the terms of the CIP are summarized below:



	Performance Share Units Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	1,027,280		$	17.24
Granted	405,014		16.90
Vested and Paid	(215,439	)	31.63
Forfeited	(17,519	)	13.88
Unvested balance at September 30, 2017	1,199,336		$	14.59

Restricted Share Units

Employees may elect to defer their grants of restricted share awards and these deferred awards are designated as restricted share units. Restricted share units vest over a three-year period and are deferred into the Company's nonqualified, unfunded deferred compensation plan at the time of vesting. These awards are ultimately delivered in cash. They are classified as liabilities and are included in "Other long-term liabilities" on the Condensed Consolidated Balance Sheets and are measured at fair value at the end of each reporting period. The weighted-average grant date fair value of the restricted share units was $16.98 and $10.12 per share for the nine months ended September 30, 2017 and 2016, respectively. As of September 30, 2017, $0.1 million of unrecognized compensation cost, which represents the unvested portion of the fair market value of restricted share units granted, is expected to be recognized over a weighted-average vesting period of 1.43 years.

Transactions involving restricted share units under the terms of the LTSIP are summarized below:



	Restricted Share Units Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	18,034		$	10.12
Granted	9,924		16.98
Vested	(6,012	)	10.12
Unvested balance at September 30, 2017	21,946		$	13.22

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Employee Benefits

9 Months Ended

Sep. 30, 2017

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Employee Benefits [Text Block]

Pension and Other Postretirement Benefits

The Company provides pension and other postretirement benefits to certain employees through three retirement benefit plans: the QEP Resources, Inc. Retirement Plan (the Pension Plan), the Supplemental Executive Retirement Plan (the SERP), and a postretirement medical plan (the Medical Plan).

The Pension Plan is a closed, qualified, defined-benefit pension plan that is funded and provides pension benefits to certain QEP employees. During the nine months ended September 30, 2017, the Company made contributions of $4.0 million to the Pension Plan and does not expect to make additional contributions to the Pension Plan during the remainder of 2017. Contributions to the Pension Plan increase plan assets. The Pension Plan was amended in June 2015 and was frozen effective January 1, 2016, such that employees do not earn additional defined benefits for future services.

The SERP is a nonqualified retirement plan that is unfunded and provides pension benefits to certain QEP employees. During the nine months ended September 30, 2017, the Company made contributions of $1.9 million to its SERP and expects to contribute an additional $0.1 million to its SERP during the remainder of 2017. Contributions to the SERP are used to fund current benefit payments. The SERP was amended and restated in June 2015 and was closed to new participants effective January 1, 2016.

During the nine months ended September 30, 2017, the Company recognized a $0.7 million loss on curtailment related to the SERP in connection with the Pinedale Divestiture, which was recorded on the Condensed Consolidated Statements of Operations within "Net gain (loss) from asset sales".

The Medical Plan is unfunded and provides other postretirement benefits including certain health care and life insurance benefits for certain retired QEP employees. During the nine months ended September 30, 2017, the Company made contributions of $0.2 million to its Medical Plan and expects to contribute an additional $0.1 million to its Medical Plan during the remainder of 2017. Contributions to the Medical Plan are used to fund current benefit payments.

In February 2017, the Company changed the eligibility requirements for active employees eligible for the Medical Plan, as well as retirees currently enrolled. Effective July 1, 2017, the Company no longer offers the Medical Plan to retirees and/or spouses that are Medicare eligible. In addition, the Company no longer offers life insurance to individuals retiring on or after July 1, 2017.

In accordance with the adoption of ASU No. 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the presentation of net periodic pension cost and net periodic postretirement benefit cost, the Company recognizes service costs related to SERP and Medical Plan benefits within "General and administrative" expense on the Condensed Consolidated Statements of Operations. All other expenses related to the Pension Plan, SERP and Medical Plan are recognized within "Interest and other income (expense)" on the Condensed Consolidated Statements of Operations.

The following table sets forth the Company’s net periodic benefit costs related to its Pension Plan, SERP and Medical Plan:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
Pension Plan and SERP benefits	(in millions)
Service cost	$	0.2		$	0.3		$	0.6		$	0.9
Interest cost	1.2			1.3			3.6			3.9
Expected return on plan assets	(1.3		)	(1.4		)	(4.0		)	(4.2		)
Amortization of prior service costs⁽¹⁾	0.3			0.3			0.9			0.9
Amortization of actuarial losses⁽¹⁾	0.1			0.2			0.3			0.6
Curtailment loss⁽²⁾	0.7			—			0.7			—
Periodic expense	$	1.2		$	0.7		$	2.1		$	2.1

Medical Plan benefits
Interest cost	$	—		$	0.1		$	0.1		$	0.2
Amortization of prior service costs⁽¹⁾	(0.1		)	—			(0.2		)	0.1
Periodic expense	$	(0.1	)	$	0.1		$	(0.1	)	$	0.3

____________________________


⁽¹⁾	Amortization of prior service costs and actuarial losses out of accumulated other comprehensive income are recognized on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)".


⁽²⁾	A curtailment is recognized immediately when there is a significant reduction in, or an elimination of, defined benefit accruals for current employees' future services. These expenses relate to the Pinedale Divestiture and are recognized on the Condensed Consolidated Statements of Operations within "Gain (loss) from asset sales" for the three and nine months ended September 30, 2017.

Subsequent Event (Notes)	9 Months Ended
Subsequent Event (Notes)	Sep. 30, 2017
Subsequent Event [Line Items]
Subsequent Events [Text Block]	On October 24, 2017, QEP closed on its previously announced acquisition of oil and gas properties in the Permian Basin for an aggregate purchase price of $683.5 million, subject to post-closing purchase price adjustments (the 2017 Permian Basin Acquisition). The 2017 Permian Basin Acquisition consists of approximately 13,000 acres, mainly in Martin County, Texas, which are held by production from existing vertical wells. Approximately 700 additional acres contracted for in the transaction were not included in the closing, but are expected to be acquired by the Company within the next 30 days for an aggregate purchase price not to exceed $38.0 million. Within 10 business days of closing the 2017 Permian Basin Acquisition, QEP is obligated to make offers to various persons who own additional oil and gas interests in certain properties included in the transaction on substantially the same terms and conditions as the purchase described above. If all offers are accepted, the aggregate purchase price is not expected to exceed $65.0 million. QEP structured the transaction as a like-kind exchange under Section 1031 of the Internal Revenue Service Code and funded all of the purchase price with the proceeds from the Pinedale Divestiture.

Acquisitions & Divestitures Purchase Accounting Entries (Tables)

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]



Consideration:
Total consideration	$	591.0

Amounts recognized for fair value of assets acquired and liabilities assumed:
Proved properties	$	406.2
Unproved properties	214.2
Asset retirement obligations	(11.6		)
Bargain purchase gain	(17.8		)
Total fair value	$	591.0

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Components of basic and diluted shares used in EPS [Table Text Block]

The following is a reconciliation of the components of basic and diluted shares used in the EPS calculation:



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2017	2016	2017	2016
	(in millions)
Weighted-average basic common shares outstanding	240.7	239.6	240.5	215.7
Potential number of shares issuable upon exercise of in-the-money stock options under the Long-Term Stock Incentive Plan	—	—	—	—
Average diluted common shares outstanding	240.7	239.6	240.5	215.7

Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2017

Asset Retirement Obligation [Abstract]

Asset retirement obligations rollforward [Table Text Block]

The following is a reconciliation of the changes in the Company's ARO for the period specified below:



	Asset Retirement Obligations
	2017
	(in millions)
ARO liability at January 1,	$	231.6
Accretion	6.0
Additions	6.2
Revisions	0.2
Liabilities related to assets sold⁽¹⁾	(40.8		)
Liabilities settled	(9.0		)
ARO liability at September 30,	$	194.2

____________________________


⁽¹⁾	Liabilities related to assets sold for the nine months ended September 30, 2017, includes $34.9 million related to the Pinedale Divestiture (refer to Note 2 – Acquisitions and Divestitures for more information).

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair value of financial assets and liabilities [Table Text Block]

The fair value of financial assets and liabilities at September 30, 2017 and December 31, 2016, is shown in the table below:



	Fair Value Measurements
	Gross Amounts of Assets and Liabilities						Netting Adjustments⁽¹⁾			Net Amounts Presented on the Condensed Consolidated Balance Sheets
	Level 1		Level 2		Level 3		Netting Adjustments⁽¹⁾
	September 30, 2017
Financial Assets	(in millions)
Fair value of derivative contracts – short-term	$	—	$	6.9	$	—	$	(3.1	)	$	3.8
Fair value of derivative contracts – long-term	—		2.5		—		(0.8		)	1.7
Total financial assets	$	—	$	9.4	$	—	$	(3.9	)	$	5.5

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	16.5	$	—	$	(3.1	)	$	13.4
Fair value of derivative contracts – long-term	—		3.2		—		(0.8		)	2.4
Total financial liabilities	$	—	$	19.7	$	—	$	(3.9	)	$	15.8

	December 31, 2016
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	—	$	—	$	—		$	—
Fair value of derivative contracts – long-term	—		—		—		—			—
Total financial assets	$	—	$	—	$	—	$	—		$	—

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	169.8	$	—	$	—		$	169.8
Fair value of derivative contracts – long-term	—		32.0		—		—			32.0
Total financial liabilities	$	—	$	201.8	$	—	$	—		$	201.8

Fair value and related carrying amount of certain financial instruments [Table Text Block]



	Carrying Amount		Level 1 Fair Value		Carrying Amount		Level 1 Fair Value
	September 30, 2017				December 31, 2016
Financial Assets	(in millions)
Cash and cash equivalents	$	782.6	$	782.6	$	443.8	$	443.8
Financial Liabilities
Checks outstanding in excess of cash balances	$	—	$	—	$	12.3	$	12.3
Long-term debt	$	2,024.6	$	2,062.1	$	2,020.9	$	2,104.3

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Derivative Contracts (Tables)

9 Months Ended

Sep. 30, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

Derivative Contracts – Production

The following table presents QEP’s volumes and average prices for its commodity derivative swap contracts as of September 30, 2017:



Year	Index	Total Volumes	Average Swap Price per Unit
		(in millions)
Oil sales		(bbls)	($/bbl)
2017	NYMEX WTI	3.6	$	51.51
2018	NYMEX WTI	14.6	$	52.42
2019	NYMEX WTI	3.7	$	50.30
Gas sales		(MMBtu)	($/MMBtu)
2017	NYMEX HH	24.8	$	2.87
2017	IFNPCR	6.4	$	2.49
2018	NYMEX HH	105.9	$	2.99
2019	NYMEX HH	14.6	$	2.87

The following table presents QEP's volumes and average prices for its commodity derivative gas collars as of September 30, 2017:

Year

Index

Total Volumes

Average Price Floor

Average Price Ceiling

(in millions)

(MMBtu)

($/MMBtu)

2017

NYMEX HH

2.8

2.50

3.50



Year	Index Less Differential	Index	Total Volumes	Weighted-Average Differential
			(in millions)
Oil sales			(bbls)	($/bbl)
2017	NYMEX WTI	Argus WTI Midland	1.1	$	(0.67	)
2018 (Full Year)	NYMEX WTI	Argus WTI Midland	7.3	$	(1.06	)
2018 (July through December)	NYMEX WTI	Argus WTI Midland	0.6	$	(0.81	)
2019	NYMEX WTI	Argus WTI Midland	2.2	$	(0.98	)
Gas sales			(MMBtu)	($/MMBtu)
2018	NYMEX HH	IFNPCR	7.3	$	(0.16	)

Derivative Contracts – Gas Storage



Year	Type of Contract	Index	Total Volumes	Average Swap Price per Unit
			(in millions)
Gas sales			(MMBtu)	($/MMBtu)
2017	SWAP	IFNPCR	1.5	$	2.88
2018	SWAP	IFNPCR	0.4	$	3.05
Gas purchases			(MMBtu)	($/MMBtu)
2017	SWAP	IFNPCR	1.1	$	2.68

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]



		Gross asset derivative instruments fair value				Gross liability derivative instruments fair value
	Balance Sheet line item	September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016
Current:		(in millions)
Commodity	Fair value of derivative contracts	$	6.9	$	—	$	16.5	$	169.8
Long-term:
Commodity	Fair value of derivative contracts	2.5		—		3.2		32.0
Total derivative instruments		$	9.4	$	—	$	19.7	$	201.8

Derivative Instruments, Gain (Loss) [Table Text Block]



	Three Months Ended						Nine Months Ended
Derivative contracts not designated as cash flow hedges	September 30,						September 30,
Derivative contracts not designated as cash flow hedges	2017			2016			2017			2016
Realized gains (losses) on commodity derivative contracts	(in millions)
Production
Oil derivative contracts	$	12.1		$	19.1		$	21.6		$	79.8
Gas derivative contracts	(0.4		)	0.4			(19.7		)	50.8
Gas Storage
Gas derivative contracts	—			0.1			(0.2		)	2.9
Realized gains (losses) on commodity derivative contracts	11.7			19.6			1.7			133.5
Unrealized gains (losses) on commodity derivative contracts
Production
Oil derivative contracts	(86.1		)	(0.3		)	88.7			(135.9		)
Gas derivative contracts	—			24.8			100.5			(80.0		)
Gas Storage
Gas derivative contracts	—			0.4			2.3			(2.7		)
Unrealized gains (losses) on commodity derivative contracts	(86.1		)	24.9			191.5			(218.6		)
Total realized and unrealized gains (losses) on commodity derivative contracts related to production and storage contracts	$	(74.4	)	$	44.5		$	193.2		$	(85.1	)

Derivatives associated with the Pinedale Divestiture⁽¹⁾
Unrealized gains (losses) on commodity derivative contracts
Production
Oil derivative contracts	$	(1.3	)	$	—		$	(1.3	)	$	—
Gas derivative contracts	(23.5		)	—			(23.5		)	—
NGL derivative contracts	(5.1		)	—			(5.1		)	—
Unrealized gains (losses) on commodity derivative contracts related to the Pinedale Divestiture	$	(29.9	)	$	—		$	(29.9	)	$	—

Total realized and unrealized gains (losses) on commodity derivative contracts	$	(104.3	)	$	44.5		$	163.3		$	(85.1	)

Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based Compensation Expense [Table Text Block]

Share-based compensation expense is recognized within "General and administrative" expense on the Condensed Consolidated Statements of Operations and is summarized in the table below:



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017			2016		2017			2016
	(in millions)
Stock options	$	0.5		$	0.6	$	1.7		$	1.8
Restricted share awards	5.4			6.0		18.7			18.2
Performance share units	(0.1		)	3.2		(6.9		)	8.8
Restricted share units	—			0.1		—			0.2
Total share-based compensation expense	$	5.8		$	9.9	$	13.5		$	29.0

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The calculated fair value of stock options granted and major assumptions used in the model at the date of grant are listed below for the nine months ended September 30, 2017:



	Stock Option Assumptions
Weighted-average grant date fair value of awards granted during the period	$	6.44
Weighted-average risk-free interest rate	1.81		%
Weighted-average expected price volatility	43.9		%
Expected dividend yield	—		%
Expected term in years at the date of grant	4.5

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

Stock option transactions under the terms of the LTSIP are summarized below:



	Options Outstanding		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
			(per share)		(in years)	(in millions)
Outstanding at December 31, 2016	2,151,957		$	25.26
Granted	418,752		16.77
Forfeited	(14,172	)	15.33
Canceled	(202,260	)	27.55
Outstanding at September 30, 2017	2,354,277		$	23.62	3.75	$	—
Options Exercisable at September 30, 2017	1,551,861		$	27.90	2.73	$	—
Unvested Options at September 30, 2017	802,416		$	15.33	5.73	$	—

Schedule of Share-based Compensation, Restricted Share Awards Activity [Table Text Block]

Transactions involving restricted share awards under the terms of the LTSIP are summarized below:



	Restricted Share Awards Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	3,208,503		$	14.32
Granted	2,123,016		14.13
Vested	(1,384,011	)	16.54
Forfeited	(240,732	)	14.71
Unvested balance at September 30, 2017	3,706,776		$	13.35



	Restricted Share Units Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	18,034		$	10.12
Granted	9,924		16.98
Vested	(6,012	)	10.12
Unvested balance at September 30, 2017	21,946		$	13.22

Schedule of Other Share-based Compensation, Activity [Table Text Block]

Transactions involving performance share units under the terms of the CIP are summarized below:



	Performance Share Units Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2016	1,027,280		$	17.24
Granted	405,014		16.90
Vested and Paid	(215,439	)	31.63
Forfeited	(17,519	)	13.88
Unvested balance at September 30, 2017	1,199,336		$	14.59

Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2017

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

The following table sets forth the Company’s net periodic benefit costs related to its Pension Plan, SERP and Medical Plan:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
Pension Plan and SERP benefits	(in millions)
Service cost	$	0.2		$	0.3		$	0.6		$	0.9
Interest cost	1.2			1.3			3.6			3.9
Expected return on plan assets	(1.3		)	(1.4		)	(4.0		)	(4.2		)
Amortization of prior service costs⁽¹⁾	0.3			0.3			0.9			0.9
Amortization of actuarial losses⁽¹⁾	0.1			0.2			0.3			0.6
Curtailment loss⁽²⁾	0.7			—			0.7			—
Periodic expense	$	1.2		$	0.7		$	2.1		$	2.1

Medical Plan benefits
Interest cost	$	—		$	0.1		$	0.1		$	0.2
Amortization of prior service costs⁽¹⁾	(0.1		)	—			(0.2		)	0.1
Periodic expense	$	(0.1	)	$	0.1		$	(0.1	)	$	0.3

____________________________


⁽¹⁾	Amortization of prior service costs and actuarial losses out of accumulated other comprehensive income are recognized on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)".


⁽²⁾	A curtailment is recognized immediately when there is a significant reduction in, or an elimination of, defined benefit accruals for current employees' future services. These expenses relate to the Pinedale Divestiture and are recognized on the Condensed Consolidated Statements of Operations within "Gain (loss) from asset sales" for the three and nine months ended September 30, 2017.

Basis of Presentation Impairment of Long-Lived Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment	$ 28.3	$ 5.0	$ 28.4	$ 1,188.2
Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment				1,167.9
Unproved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment				16.6
Pinedale [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment				1,164.0
Other Northern [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment				3.5
Other Southern [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment				0.4
Williston & Permian Basins [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill impairment				$ 3.7

Acquisitions & Divestitures 2016 Permian Basin Acquisition (Details) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) a	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Bargain purchase gain from acquisition		$ (0.4)	$ 4.4
2016 Permian Basin Acquisition [Member]
Business Acquisition [Line Items]
Payments for acquisitions		591.0
Net acres \| a			9,600
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 18.8	38.6
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ 3.5	5.4
Bargain purchase gain from acquisition		$ (0.4)		$ (18.2)

Acquisitions & Divestitures Purchase Accounting Entries (Details) - 2016 Permian Basin Acquisition [Member] $ in Millions	Sep. 30, 2017 USD ($)
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$ 591.0
Proved Property [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	406.2
Unproved Property [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	214.2
Asset Retirement Obligation Costs [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	(11.6)
Bargain Purchase Gain [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$ (17.8)

Acquisitions & Divestitures Pro Forma (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues	$ 390.1	$ 382.4	$ 1,193.9	$ 977.4
Net income (loss)	$ (3.3)	$ (50.9)	$ 119.0	$ (1,111.7)
Earnings Per Share, Basic	$ (0.01)	$ (0.21)	$ 0.49	$ (5.15)
Earnings Per Share, Diluted	$ (0.01)	$ (0.21)	$ 0.49	$ (5.15)
2016 Permian Basin Acquisition [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues		$ 382.4		$ 977.4
Net income (loss)		$ (50.9)		$ (1,111.7)
Earnings Per Share, Basic		$ (0.21)		$ (5.15)
Earnings Per Share, Diluted		$ (0.21)		$ (5.15)
Pro Forma Revenue		$ 387.3		$ 991.9
Pro Forma Net Income (Loss)		$ (51.3)		$ (1,113.4)
Pro Forma Earnings Per Share, Basic		$ (0.21)		$ (5.16)
Pro Forma Earnings Per Share, Diluted		$ (0.21)		$ (5.16)

Acquisitions & Divestitures Other Acquisitions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Bargain purchase gain from acquisition	$ (0.4)	$ 4.4
Payments to acquire oil and gas property	94.5	39.9
Other Acquisitions [Member]
Business Acquisition [Line Items]
Bargain purchase gain from acquisition		4.4
Acquisition Costs, Period Cost	94.5	46.1
Goodwill	$ 5.3	3.7
Cash [Member] \| Other Acquisitions [Member]
Business Acquisition [Line Items]
Payments to acquire oil and gas property		39.9
Accounts Receivable [Member] \| Other Acquisitions [Member]
Business Acquisition [Line Items]
Payments to acquire oil and gas property		$ (6.2)

Acquisitions & Divestitures Pinedale Divestiture (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Divestitures [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment			$ 787.9	$ 28.9
Net gain (loss) from asset sales	$ 185.4	$ 5.3	205.2	5.0
Minimum volume commitment			45.0
INCOME (LOSS) BEFORE INCOME TAXES	(6.5)	(79.9)	188.7	(1,752.9)
Total [Member]
Divestitures [Line Items]
Minimum volume commitment remaining	35.0		35.0
Short-term [Member]
Divestitures [Line Items]
Minimum volume commitment remaining	28.0		28.0
Long-term [Member]
Divestitures [Line Items]
Minimum volume commitment remaining	7.0		7.0
Pinedale Divestiture [Member]
Divestitures [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment			718.2
Net gain (loss) from asset sales			178.8
INCOME (LOSS) BEFORE INCOME TAXES	208.2	$ 19.2	251.2	(1,177.0)
Restructuring costs, expected cost	0.8		0.8
One-time Termination Benefits [Member] \| Pinedale Divestiture [Member]
Divestitures [Line Items]
Restructuring costs, expected cost	0.5		0.5
Restructuring costs, cost incurred to date	0.5		0.5
Employee Relocation [Member] \| Pinedale Divestiture [Member]
Divestitures [Line Items]
Restructuring costs, expected cost	$ 0.3		$ 0.3
Proved Property [Member]
Divestitures [Line Items]
Impairment				1,167.9
Proved Property [Member] \| Pinedale [Member]
Divestitures [Line Items]
Impairment				$ 1,164.0

Acquisitions & Divestitures Other Divestitures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Divestitures [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment			$ 787.9	$ 28.9
Net gain (loss) from asset sales	$ 185.4	$ 5.3	205.2	5.0
Payments to acquire oil and gas property			94.5	$ 39.9
Non-core properties Divestitures [Member]
Divestitures [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment			69.7
Net gain (loss) from asset sales			$ 26.4

Earnings Per Share Components of Basic and Diluted Shares Used In EPS Calculation (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Anti-dilutive shares	0.0	0.2	0.0	0.1
Weighted-average basic common shares outstanding	240.7	239.6	240.5	215.7
Potential number of shares issuable upon exercise of in-the-money stock options under the Long-term Stock Incentive Plan	0.0	0.0	0.0	0.0
Average diluted common shares outstanding	240.7	239.6	240.5	215.7

Capitalized Exploratory Well Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Capitalized Exploratory Well Costs [Line Items]
Capitalized exploratory well costs charged to expense			$ 21.2	$ 0.0
Impairment	$ 28.3	$ 5.0	28.4	$ 1,188.2
Central Basin Platform [Member]
Capitalized Exploratory Well Costs [Line Items]
Reclassifications to proved properties			(3.6)
Capitalized exploratory well costs charged to expense			(21.2)
Impairment			$ 28.3

Capitalized Exploratory Well Costs Capitalized Exploratory Well Costs Table (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Capitalized Exploratory Well Costs [Line Items]
Capitalized exploratory well costs, beginning balance	$ 14.2
Additions to capitalized exploratory well costs	10.6
Capitalized exploratory well costs charged to expense	21.2	$ 0.0
Capitalized exploratory well costs, ending balance	0.0
Central Basin Platform [Member]
Capitalized Exploratory Well Costs [Line Items]
Reclassifications to proved properties	(3.6)
Capitalized exploratory well costs charged to expense	$ (21.2)

Asset Retirement Obligations (Details) - USD ($)
$ in Millions

9 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Divestitures [Line Items]

Asset Retirement Obligation, Current

$ 4.9

$ 5.8

ARO Liability [Roll Forward]

ARO liability, Beginning Balance

231.6

Accretion

6.0

Additions

6.2

Revisions

0.2

Liabilities related to assets sold

^[1]

(40.8)

Liabilities settled

(9.0)

ARO liability, Ending Balance

194.2

Pinedale Divestiture [Member]

ARO Liability [Roll Forward]

Liabilities related to assets sold

$ 34.9

[1]	Liabilities related to assets sold for the nine months ended September 30, 2017, includes $34.9 million related to the Pinedale Divestiture (refer to Note 2 – Acquisitions and Divestitures for more information).

Fair Value Measurements Fair Value of Financial Assets and Liabilities (Details) - USD ($)
$ in Millions

9 Months Ended

Sep. 30, 2016

Sep. 30, 2017

Dec. 31, 2016

Financial Assets

Derivative Asset

$ 5.5

$ 0.0

Net amount of derivative assets presented on condensed consolidated balance sheets

^[1]

(3.9)

0.0

Derivative Liability

15.8

201.8

Level 1 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Level 2 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

9.4

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

19.7

201.8

Level 3 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Long-term [Member]

Financial Assets

Derivative Asset

1.7

0.0

Net amount of derivative assets presented on condensed consolidated balance sheets

^[1]

(0.8)

0.0

Derivative Liability

2.4

32.0

Long-term [Member] | Level 1 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Long-term [Member] | Level 2 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

2.5

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

3.2

32.0

Long-term [Member] | Level 3 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Short-term [Member]

Financial Assets

Derivative Asset

3.8

0.0

Net amount of derivative assets presented on condensed consolidated balance sheets

^[1]

(3.1)

0.0

Derivative Liability

13.4

169.8

Short-term [Member] | Level 1 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Short-term [Member] | Level 2 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

6.9

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

16.5

169.8

Short-term [Member] | Level 3 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

$ 0.0

Proved Property [Member]

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Impairment

$ 1,167.9

[1]

The Company nets its derivative contract assets and liabilities outstanding with the same counterparty on the Condensed Consolidated Balance Sheets, for the contracts that contain netting provisions. See Note 7 – Derivative Contracts for additional information regarding the Company's derivative contracts.

Fair Value Measurements Fair Value and Related Carrying Amount of Certain Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 782.6	$ 443.8
Checks outstanding in excess of cash balances	0.0	12.3
Long-term debt	2,024.6	2,020.9
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	782.6	443.8
Checks outstanding in excess of cash balances	0.0	12.3
Long-term debt, fair value	$ 2,062.1	$ 2,104.3

Derivative Contracts (Narrative) (Details)	9 Months Ended
Derivative Contracts (Narrative) (Details)	Sep. 30, 2017
Derivative [Line Items]
Maximum Forecasted Production Covered By Derivatives	100.00%
Minimum [Member]
Derivative [Line Items]
Expected Annual Production Covered By Derivatives	50.00%
Maximum [Member]
Derivative [Line Items]
Expected Annual Production Covered By Derivatives	75.00%

Derivative Contracts Schedule Of Commodity Derivative Contracts (Details) MMBTU in Millions	9 Months Ended
	Sep. 30, 2017 USD ($) MMBTU $ / MMBTU
Oil Basis Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	1.1
Weighted-Average Differential \| $ / MMBTU	(0.67)
Oil Basis Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	7.3
Weighted-Average Differential \| $ / MMBTU	(1.06)
Oil Basis Swaps [Member] \| Production [Member] \| Year 2018 (July through December) [Member] \| NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	0.6
Weighted-Average Differential \| $ / MMBTU	(0.81)
Oil Basis Swaps [Member] \| Production [Member] \| Year 2019 [Member] \| NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	2.2
Weighted-Average Differential \| $ / MMBTU	(0.98)
Gas Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	24.8
Average Swap Price per Unit \| $	$ 2.87
Gas Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	6.4
Average Swap Price per Unit \| $	$ 2.49
Gas Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	105.9
Average Swap Price per Unit \| $	$ 2.99
Gas Swaps [Member] \| Production [Member] \| Year 2019 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	14.6
Average Swap Price per Unit \| $	$ 2.87
Gas Swaps [Member] \| Storage [Member] \| Year 2017 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	1.5
Average Swap Price per Unit \| $	$ 2.88
Gas Swaps [Member] \| Storage [Member] \| Year 2018 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	0.4
Average Swap Price per Unit \| $	$ 3.05
Oil Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	3.6
Average Swap Price per Unit \| $	$ 51.51
Oil Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	14.6
Average Swap Price per Unit \| $	$ 52.42
Oil Swaps [Member] \| Production [Member] \| Year 2019 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	3.7
Average Swap Price per Unit \| $	$ 50.30
Gas Collars [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	2.8
Derivative Average Price Floor \| $	$ 2.50
Derivative Average Price Ceiling \| $	$ 3.50
Gas Basis Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX HH LESS IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	7.3
Weighted-Average Differential \| $ / MMBTU	(0.16)
Gas Purchase Swaps [Member] \| Storage [Member] \| Year 2018 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	1.1
Average Swap Price per Unit \| $	$ 2.68

Derivative Contracts Schedule of Derivatives Financial Statement Presentation (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 9.4	$ 0.0
Derivative Liability, Fair Value, Gross	19.7	201.8
Short-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	6.9	0.0
Derivative Liability, Fair Value, Gross	16.5	169.8
Long-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	2.5	0.0
Derivative Liability, Fair Value, Gross	3.2	32.0
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	9.4	0.0
Derivative Liability, Fair Value, Gross	19.7	201.8
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member] \| Short-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	6.9	0.0
Derivative Liability, Fair Value, Gross	16.5	169.8
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member] \| Long-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	2.5	0.0
Derivative Liability, Fair Value, Gross	$ 3.2	$ 32.0

Derivative Contracts Gain (Loss) in Statement of Financial Performance (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Derivative [Line Items]

Realized gain (loss) on commodity derivative contracts not designated as hedging instruments

$ 11.7

$ 19.6

$ 1.7

$ 133.5

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

(86.1)

24.9

191.5

(218.6)

Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments

(104.3)

44.5

163.3

(85.1)

Oil derivative contracts [Member] | Production [Member]

Derivative [Line Items]

Realized gain (loss) on commodity derivative contracts not designated as hedging instruments

12.1

19.1

21.6

79.8

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

(86.1)

(0.3)

88.7

(135.9)

Natural gas derivative contracts [Member] | Production [Member]

Derivative [Line Items]

Realized gain (loss) on commodity derivative contracts not designated as hedging instruments

(0.4)

0.4

(19.7)

50.8

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

0.0

24.8

100.5

(80.0)

Natural gas derivative contracts [Member] | Storage [Member]

Derivative [Line Items]

Realized gain (loss) on commodity derivative contracts not designated as hedging instruments

0.0

0.1

(0.2)

2.9

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

0.0

0.4

2.3

(2.7)

Pinedale Divestiture [Member]

Derivative [Line Items]

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

^[1]

(29.9)

0.0

(29.9)

0.0

Pinedale Divestiture [Member] | NGL derivative contracts [Member] | Production [Member]

Derivative [Line Items]

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

^[1]

(5.1)

0.0

(5.1)

0.0

Pinedale Divestiture [Member] | Oil derivative contracts [Member] | Production [Member]

Derivative [Line Items]

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

^[1]

(1.3)

0.0

(1.3)

0.0

Pinedale Divestiture [Member] | Natural gas derivative contracts [Member] | Production [Member]

Derivative [Line Items]

Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments

^[1]

(23.5)

0.0

(23.5)

0.0

Total [Member]

Derivative [Line Items]

Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments

$ (74.4)

$ 44.5

$ 193.2

$ (85.1)

[1]

Debt (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Debt (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt Maturity Period	5 years
Principal amount of senior notes outstanding	$ 2,045.0
Debt Instrument, Maturity Date Range, Start	Apr. 01, 2018
Debt Instrument, Maturity Date Range, End	May 01, 2023
Senior Notes, stated interest rate, minimum (in hundredths)	5.25%
Senior Notes, stated interest rate, maximim (in hundredths)	6.875%
Revolving Credit Facility due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 0.0	$ 0.0
Maturity date of long-term debt	Dec. 02, 2019
Borrowing capacity	$ 1,800.0
Letters of credit outstanding	1.0	2.8
6.80% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 134.0	134.0
Long-term debt, interest rate (in hundredths)	6.80%
Maturity date of long-term debt	Apr. 01, 2018
6.80% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 136.0	136.0
Long-term debt, interest rate (in hundredths)	6.80%
Maturity date of long-term debt	Mar. 01, 2020
6.875% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 625.0	$ 625.0
Long-term debt, interest rate (in hundredths)	6.875%
Maturity date of long-term debt	Mar. 01, 2021

Debt Schedule of Debt Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Less unamortized discount	$ (20.4)	$ (24.1)
Long-term debt	2,024.6	2,020.9
Total long-term debt outstanding	1,890.6	2,020.9
Less: current portion of long-term debt	(134.0)	0.0
Revolving Credit Facility due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0.0	0.0
6.80% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	134.0	134.0
6.80% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	136.0	136.0
6.875% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	625.0	625.0
5.375% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	500.0	500.0
5.25% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 650.0	$ 650.0

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants	5.1
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs	$ 2.1
Weighted average vesting period	2 years 2 months 23 days
Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 14.13	$ 10.37
Unrecognized compensation costs	$ 25.2
Weighted average vesting period	2 years 2 months 1 day
Award vesting period	3 years
Total fair value of stock that vested during the period	$ 22.9	$ 24.2
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 16.90	$ 10.16
Unrecognized compensation costs	$ 0.2
Weighted average vesting period	2 years 11 days
Restricted Share Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 16.98	$ 10.12
Unrecognized compensation costs	$ 0.1
Weighted average vesting period	1 year 5 months 5 days

Share-Based Compensation Share-based compensation expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 5.8	$ 9.9	$ 13.5	$ 29.0
Stock Options [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	0.5	0.6	1.7	1.8
Restricted Share Awards [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	5.4	6.0	18.7	18.2
Performance Share Units [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	(0.1)	3.2	(6.9)	8.8
Restricted Share Units (RSUs) [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 0.0	$ 0.1	$ 0.0	$ 0.2

Share-Based Compensation Fair Value Of Options Granted And Major Assumptions Used (Details)	9 Months Ended
	Sep. 30, 2017 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of awards granted during the period	$ 6.44
Weighted-average risk-free interest rate	1.81%
Weighted-average expected price volatility	43.90%
Expected dividend yield	0.00%
Expected term in years at the date of grant	4 years 6 months

Share-Based Compensation Schedule Of Stock Option Transactions (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period \| shares	2,151,957
Options granted \| shares	418,752
Options forfeited \| shares	(14,172)
Options canceled \| shares	(202,260)
Outstanding at end of period \| shares	2,354,277
Options exercisable, shares \| shares	1,551,861
Unvested options, shares \| shares	802,416
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average exercise price, beginning of year \| $ / shares	$ 25.26
Weighted average exercise price, granted in period \| $ / shares	16.77
Weighted average exercise price, forfeited in period \| $ / shares	15.33
Weighted average exercise price, canceled in period \| $ / shares	27.55
Weighted average exercise price, end of year \| $ / shares	23.62
Options exercisable, weighted average exercise price \| $ / shares	27.90
Unvested options, weighted average exercise price \| $ / shares	$ 15.33
Weighted average remaining contractual term, options outstanding	3 years 9 months
Weighted average remaining contractual term, options exercisable	2 years 8 months 23 days
Weighted average remaining contractual term, options unvested	5 years 8 months 23 days
Aggregate intrinsic value, options outstanding \| $	$ 0.0
Aggregate intrinsic value, options exercisable \| $	0.0
Aggregate intrinsic value, options unvested \| $	$ 0.0

Share-Based Compensation Schedule of Restricted Share Awards Transactions (Details) - Restricted Share Awards [Member] - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested balance at beginning of period	3,208,503
Shares granted	2,123,016
Shares vested	(1,384,011)
Shares forfeited	(240,732)
Unvested balance at end of period	3,706,776
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Weighted average grant date fair value, beginning of period	$ 14.32
Weighted average grant date fair value, grants	14.13	$ 10.37
Weighted average grant date fair value, vested	16.54
Weighted average grant date fair value, forfeited	14.71
Weighted average grant date fair value, end of period	$ 13.35

Share-Based Compensation Schedule Of Performance Share Unit Transactions (Details) - Performance Share Units [Member] - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested balance at beginning of period	1,027,280
Shares granted	405,014
Shares vested	(215,439)
Shares forfeited	(17,519)
Unvested balance at end of period	1,199,336
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Weighted average grant date fair value, beginning of period	$ 17.24
Weighted average grant date fair value, grants	16.90	$ 10.16
Weighted average grant date fair value, vested	31.63
Weighted average grant date fair value, forfeited	13.88
Weighted average grant date fair value, end of period	$ 14.59

Share-Based Compensation Schedule of Restricted Share Unit Transactions (Details) - Restricted Share Units (RSUs) [Member] - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested balance at beginning of period	18,034
Shares granted	9,924
Shares vested	(6,012)
Unvested balance at end of period	21,946
Weighted average grant date fair value, beginning of period	$ 10.12
Weighted average grant date fair value, grants	16.98	$ 10.12
Weighted average grant date fair value, vested	10.12
Weighted average grant date fair value, end of period	$ 13.22

Employee Benefits (Narrative) (Details) $ in Millions	9 Months Ended
Employee Benefits (Narrative) (Details) $ in Millions	Sep. 30, 2017 USD ($)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	$ 4.0
SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	1.9
Estimated Future Employer Contributions in Current Fiscal Year	0.1
Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer	0.2
Estimated Future Employer Contributions in Current Fiscal Year	0.1
Pinedale Divestiture [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Curtailment loss	$ 0.7

Employee Benefits Schedule of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Pension Plan and SERP [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Service cost

$ 0.2

$ 0.3

$ 0.6

$ 0.9

Interest cost

1.2

1.3

3.6

3.9

Expected return on plan assets

(1.3)

(1.4)

(4.0)

(4.2)

Amortization of prior service costs

^[1]

0.3

0.9

Amortization of actuarial losses

^[1]

0.1

0.2

0.3

0.6

Curtailment loss

^[2]

0.7

0.0

0.7

0.0

Periodic expense

1.2

0.7

2.1

Medical Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Interest cost

0.0

0.1

0.2

Amortization of prior service costs

^[1]

(0.1)

0.0

(0.2)

0.1

Periodic expense

$ (0.1)

$ 0.1

$ (0.1)

$ 0.3

[1]	Amortization of prior service costs and actuarial losses out of accumulated other comprehensive income are recognized on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)".
[2]	A curtailment is recognized immediately when there is a significant reduction in, or an elimination of, defined benefit accruals for current employees' future services. These expenses relate to the Pinedale Divestiture and are recognized on the Condensed Consolidated Statements of Operations within "Gain (loss) from asset sales" for the three and nine months ended September 30, 2017.

Subsequent Event (Details) $ in Millions	9 Months Ended
Subsequent Event (Details) $ in Millions	Sep. 30, 2017 USD ($) a
2017 Permian Basin Acquisition [Member]
Subsequent Event [Line Items]
Payments for acquisitions	$ 683.5
Net acres \| a	13,000
Permian Basin Acquisition [Member]
Subsequent Event [Line Items]
Payments for acquisitions	$ 38.0
Net acres \| a	700
Additional acquisitions in the Permian Basin [Member]
Subsequent Event [Line Items]
Payments for acquisitions	$ 65.0

Basis of Presentation Income Taxes (Details)	3 Months Ended
Basis of Presentation Income Taxes (Details)	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	49.20%