Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2016 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	239,557,986
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
REVENUES
Gas sales	$ 123.2	$ 129.4	$ 287.5	$ 363.3
Oil sales	201.6	211.7	553.1	640.9
NGL sales	19.8	16.5	56.2	61.7
Other revenue	2.5	2.8	4.3	12.4
Purchased gas and oil sales	35.3	147.2	76.3	472.0
Total Revenues	382.4	507.6	977.4	1,550.3
OPERATING EXPENSES
Purchased gas and oil expense	37.1	146.0	80.8	475.1
Lease operating expense	50.7	56.7	163.3	175.6
Gas, oil and NGL transportation and other handling costs	75.8	78.1	218.9	216.2
Gathering and other expense	0.9	1.3	3.8	4.4
General and administrative	67.0	42.0	159.4	140.7
Production and property taxes	26.8	30.2	65.3	90.7
Depreciation, depletion and amortization	217.8	238.1	667.5	649.3
Exploration expenses	0.2	0.8	0.9	2.7
Impairment	5.0	15.0	1,188.2	35.5
Total operating expenses	481.3	608.2	2,548.1	1,790.2
Net gain (loss) from asset sales	5.3	12.9	5.0	6.9
OPERATING INCOME (LOSS)	(93.6)	(87.7)	(1,565.7)	(233.0)
Realized and unrealized gains (losses) on derivative contracts (Note 7)	44.5	153.6	(85.1)	168.5
Interest and other income (expense)	5.1	0.3	7.1	1.5
Interest expense	(35.9)	(36.4)	(109.2)	(109.4)
INCOME (LOSS) BEFORE INCOME TAXES	(79.9)	29.8	(1,752.9)	(172.4)
Income tax (provision) benefit	29.0	(8.7)	641.2	61.6
NET INCOME (LOSS)	$ (50.9)	$ 21.1	$ (1,111.7)	$ (110.8)
Earnings per common share
Earnings Per Share, Basic	$ (0.21)	$ 0.12	$ (5.15)	$ (0.63)
Earnings Per Share, Diluted	$ (0.21)	$ 0.12	$ (5.15)	$ (0.63)
Weighted-average common shares outstanding
Used in basic calculation (in shares)	239.6	176.7	215.7	176.5
Used in diluted calculation (in shares)	239.6	176.7	215.7	176.5
Dividends per common share (in dollars per share)	$ 0.00	$ 0.02	$ 0.00	$ 0.06

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

3 Months Ended

9 Months Ended

Sep. 30, 2016

Sep. 30, 2015

Sep. 30, 2016

Sep. 30, 2015

Statement of Comprehensive Income [Abstract]

Net income (loss)

$ (50.9)

$ 21.1

$ (1,111.7)

$ (110.8)

Pension and other postretirement plans adjustments:

Amortization of prior service costs

^[1]

0.2

0.3

0.6

0.9

Amortization of net actuarial losses

^[2]

0.1

0.0

0.3

0.2

Other comprehensive income

0.3

0.9

1.1

Comprehensive income (loss)

(50.6)

21.4

(1,110.8)

(109.7)

Amortization of prior service cost, income tax expense

(0.1)

(0.3)

(0.5)

Amortization of net actuarial loss, income tax expense

$ (0.1)

$ 0.0

$ (0.3)

$ (0.2)

[1]	Presented net of income tax expense of $0.1 million and $0.3 million during the three and nine months ended September 30, 2016, respectively. Presented net of income tax expense of $0.1 million and $0.5 million during the three and nine months ended September 30, 2015, respectively.
[2]	Presented net of income tax expense of $0.1 million and $0.3 million during the three and nine months ended September 30, 2016, respectively. Presented net of income tax expense of $0.2 million for the nine months ended September 30, 2015.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension and other postretirement plans adjustments:
Amortization of net actuarial loss, income tax expense	$ (0.1)	$ 0.0	$ (0.3)	$ (0.2)
Amortization of prior service cost, income tax expense	$ (0.1)	$ (0.1)	$ (0.3)	$ (0.5)

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 1,032.2	$ 376.1
Accounts receivable, net	135.6	278.2
Income tax receivable	22.5	87.3
Fair value of derivative contracts	0.5	146.8
Gas, oil and NGL inventories at lower of average cost or market	10.8	13.3
Prepaid expenses and other	7.4	30.1
Total Current Assets	1,209.0	931.8
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	13,684.0	13,314.9
Unproved properties	658.5	691.0
Marketing and other	300.7	297.9
Material and supplies	31.7	38.5
Total Property, Plant and Equipment	14,674.9	14,342.3
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	8,604.7	6,870.2
Marketing and other	99.6	87.5
Total Accumulated Depreciation, Depletion and Amortization	8,704.3	6,957.7
Net Property, Plant and Equipment	5,970.6	7,384.6
Fair value of derivative contracts	0.0	23.2
Other noncurrent assets	95.6	58.6
TOTAL ASSETS	7,275.2	8,398.2
Current Liabilities
Checks outstanding in excess of cash balances	4.3	29.8
Accounts payable and accrued expenses	259.3	351.7
Production and property taxes	40.3	46.1
Interest payable	32.8	36.4
Fair value of derivative contracts	34.5	0.8
Current portion of long-term debt	0.0	176.8
Total Current Liabilities	371.2	641.6
Long-term debt	2,019.3	2,014.7
Deferred income taxes	899.2	1,479.8
Asset retirement obligations	213.1	204.9
Fair value of derivative contracts	19.4	4.0
Other long-term liabilities	117.9	105.3
Commitments and contingencies (Note 10)
EQUITY
Common stock – par value $0.01 per share; 500.0 million shares authorized; 240.7 million and 177.3 million shares issued, respectively	2.4	1.8
Treasury stock – 1.1 million and 0.5 million shares, respectively	(22.2)	(14.6)
Additional paid-in capital	1,359.8	554.8
Retained earnings	2,306.6	3,418.3
Accumulated other comprehensive income (loss)	(11.5)	(12.4)
Total Shareholders' Equity	3,635.1	3,947.9
TOTAL LIABILITIES AND EQUITY	$ 7,275.2	$ 8,398.2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares shares in Millions	Sep. 30, 2016	Dec. 31, 2015
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)	240.7	177.3
Treasury stock (in shares)	1.1	0.5

UNAUDITED STATEMENT OF EQUITY Statement - 9 months ended Sep. 30, 2016 - USD ($) shares in Millions, $ in Millions	Total	Common Stock, Value [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Stockholders' Equity at Dec. 31, 2015	$ 3,947.9	$ 1.8	$ (14.6)	$ 554.8	$ 3,418.3	$ (12.4)
Shares, Issued at Dec. 31, 2015		177.3
Treasury Stock, Shares at Dec. 31, 2015	(0.5)		(0.5)
Net income	$ (1,111.7)	$ 0.0	$ 0.0	0.0	(1,111.7)	0.0
Stockholders' Equity, Other Shares		0.0	0.0
Stock Issued During Period, Shares, New Issues		61.0	0.0
Stock Issued During Period, Value, New Issues	781.6	$ 0.6	$ 0.0	781.0	0.0	0.0
Stock Issued During Period, Shares, Treasury Stock Reissued			(0.6)
Stock Granted, Value, Share-based Compensation, Net of Forfeitures		$ 0.0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		2.4
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	16.4		$ (7.6)	24.0	0.0	0.0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	0.9	$ 0.0	0.0	0.0	0.0	0.9
Stockholders' Equity at Sep. 30, 2016	$ 3,635.1	$ 2.4	$ (22.2)	$ 1,359.8	$ 2,306.6	$ (11.5)
Shares, Issued at Sep. 30, 2016		240.7
Treasury Stock, Shares at Sep. 30, 2016	(1.1)		(1.1)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
OPERATING ACTIVITIES
Net income (loss)	$ (1,111.7)	$ (110.8)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	667.5	649.3
Deferred income taxes	(581.1)	22.7
Impairment	1,188.2	35.5
Bargain purchase gain from acquisition	(4.4)	0.0
Share-based compensation	29.0	23.3
Other Operating Activities, Curtailment Loss	0.0	11.2
Amortization of debt issuance costs and discounts	4.8	4.7
Net (gain) loss from asset sales	(5.0)	(6.9)
Unrealized (gains) losses on marketable securities	(1.2)	0.0
Unrealized (gains) losses on derivative contracts	218.6	148.0
Changes in operating assets and liabilities	128.2	(503.1)
Net Cash Provided by (Used in) Operating Activities	532.9	273.9
INVESTING ACTIVITIES
Property acquisitions	(39.9)	(23.5)
Acquisition Deposit Held In Escrow	(30.0)	0.0
Property, plant and equipment, including dry exploratory well expense	(411.2)	(862.6)
Proceeds from disposition of assets	28.9	5.2
Net Cash Provided by (Used in) Investing Activities	(452.2)	(880.9)
FINANCING ACTIVITIES
Checks outstanding in excess of cash balances	(25.5)	(41.9)
Repayments of Long-term Debt	(176.8)	0.0
Treasury stock repurchases	(4.1)	(2.3)
Dividends paid	0.0	(10.6)
Proceeds from issuance of common stock, net	781.6	0.0
Excess tax (provision) benefit on share-based compensation	0.2	(2.4)
Net Cash Provided by (Used in) Financing Activities	575.4	(57.3)
Change in cash and cash equivalents	656.1	(664.3)
Beginning cash and cash equivalents	376.1	1,160.1
Ending cash and cash equivalents	1,032.2	495.8
Supplemental Disclosures:
Cash paid for interest, net of capitalized interest	107.0	107.4
Cash paid (refund received) for income taxes	(123.3)	492.3
Non-cash Investing Activities
Change in capital expenditure accruals and other non-cash adjustments	$ (20.4)	$ (68.9)

Basis of Presentation

9 Months Ended

Sep. 30, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation [Text Block]

Nature of Business

QEP Resources, Inc. is an independent natural gas and crude oil exploration and production company focused in two regions of the United States: the Northern Region (primarily in Wyoming, 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 United States Generally Accepted Accounting Principles (GAAP) and with the instructions for Quarterly Reports on Form 10-Q and Regulations S-X and S-K. 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, 2015.

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, 2016, are not necessarily indicative of the results that may be expected for the year ending December 31, 2016.

Equity Offerings

In June 2016, QEP issued 23.0 million shares of common stock through a public offering and received net proceeds of approximately $413.0 million. In October, QEP used the net proceeds from this offering to partially fund the 2016 Permian Acquisition (see Note 13 – Subsequent Event).

In March 2016, QEP issued 37.95 million shares of common stock through a public offering and received net proceeds of approximately $368.6 million. QEP used the net proceeds from this offering for general corporate purposes.

Termination of Marketing Agreements and QEP Marketing Segment

Effective January 1, 2016, QEP terminated its contracts for resale and marketing transactions between its wholly owned subsidiaries, QEP Marketing Company (QEP Marketing) and QEP Energy Company (QEP Energy). In addition, substantially all of QEP Marketing's third-party purchase and sale agreements and gathering, processing and transportation contracts were assigned to QEP Energy, except those contracts related to natural gas storage activities and the Haynesville gathering system. As a result, QEP Energy is directly marketing its own gas, oil and NGL production. While QEP will continue to act as an agent for the sale of gas, oil and NGL production for other working interest owners, for whom QEP serves as the operator, QEP is no longer the first purchaser of this production. QEP has substantially reduced its marketing activities, and subsequently, is reporting lower resale revenue and expenses than it had in prior periods. In conjunction with the changes described above, QEP conducted a segment analysis in accordance with Accounting Standards Codification (ASC) Topic 280, Segment Reporting, and determined that QEP has one reportable segment effective January 1, 2016.

Revision of Financial Statements

In the fourth quarter of 2015, the Company determined that certain transactions that had been reported on a gross basis and included in "Purchased gas and oil sales" and "Purchased gas and oil expense" on the Condensed Consolidated Statement of Operations for the three and nine months ended September 30, 2015, should have been reported on a net basis, as the transactions were with the same counterparty and were entered into in contemplation of one another. The Company revised its financial statements to reflect the net accounting treatment and assessed the cumulative impact of the revisions on each period affected. The revisions had no effect on the Company’s operating income, net income, earnings per share, cash flows or retained earnings. The Company determined that the impact of the change from gross to net accounting was not material, either individually or in the aggregate, to previously issued financial statements. The Company has, for comparability purposes, recast its Condensed Consolidated Statement of Operations for the three and nine months ended September 30, 2015.

The following table details the impact of these revisions for the three and nine months ended September 30, 2015, on the Condensed Consolidated Statement of Operations.



	Three Months Ended							Nine Months Ended
	September 30, 2015							September 30, 2015
	As reported		As revised		Change			As reported		As revised		Change
REVENUES	(in millions)
Purchased gas and oil sales	$	176.3	$	147.2	$	(29.1	)	$	558.6	$	472.0	$	(86.6	)
Total Revenues	536.7		507.6		(29.1		)	1,636.9		1,550.3		(86.6		)
OPERATING EXPENSES
Purchased gas and oil expense	$	175.1	$	146.0	$	(29.1	)	$	561.7	$	475.1	$	(86.6	)
Total Operating Expenses	637.3		608.2		(29.1		)	1,876.8		1,790.2		(86.6		)

Reclassifications

Certain prior period balances on the Condensed Consolidated Balance Sheets have been reclassified to conform to the current year presentation. Such reclassifications had no effect on the Company's operating income, net income, earnings per share, cash flows or retained earnings previously reported.

Impairment of Long-Lived Assets

During the three months ended September 30, 2016, QEP recorded impairment expense of $5.0 million, all of which was related to expiring leaseholds on unproved properties.

During the nine months ended September 30, 2016, QEP recorded impairment expense 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.

New Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 disclosing key quantitative and qualitative information about leasing arrangements. The amendment will be effective for reporting periods beginning on or 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 will be effective prospectively for reporting periods beginning on or after December 31, 2016, and early adoption is permitted. The Company does not expect this ASU to have a material impact on the Company's Condensed Consolidated Financial Statements.

In March 2016, the FASB issued ASU No. 2016-08, Revenue from contracts with customers (Topic 606): Principal versus agent considerations (reporting revenue gross versus net), which clarifies the implementation guidance on principle versus agent considerations. The amendment will be effective prospectively for reporting periods beginning on or after December 31, 2017, and early adoption is permitted for periods beginning on or after December 31, 2016. 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. 2016-09, 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 will be effective prospectively for reporting periods beginning on or after December 15, 2016, and early adoption is permitted. The Company does not expect this ASU to have a material impact on the Company's Condensed Consolidated Financial Statements.

In April 2016, the FASB issued ASU No. 2016-10, Revenue from contracts with customers (Topic 606): Identifying performance obligations and licensing, which clarifies guidance related to identifying performance obligations and licensing implementation guidance contained in the new revenue recognition standard. This amendment will be effective prospectively for reporting periods beginning on or after December 15, 2017, and early adoption is permitted for periods beginning on or after December 31, 2016. The Company is currently assessing the impact of the ASU on the Company's Condensed Consolidated Financial Statements.

In May 2016, the FASB issued ASU No. 2016-11, Revenue recognition (Topic 605) and Derivatives and hedging (Topic 815): Rescission of SEC guidance because of ASU 2014-09 and 2014-16, which rescinds certain SEC staff observer comments that are codified in Topic 605, Revenue Recognition. This amendment will be effective prospectively for reporting periods beginning on or after December 15, 2017, and early adoption is permitted for periods beginning on or after December 31, 2016. The Company is currently assessing the impact of the ASU on the Company's Condensed Consolidated Financial Statements.

In May 2016, the FASB issued ASU No. 2016-12, Revenue from contracts with customers (Topic 606): Narrow-scope improvements and practical expedients, which intends to reduce the cost and complexity of applying the new revenue standard by narrowing the scope of improvements to the guidance on collectability, non-cash consideration, and completed contracts at transition. This amendment will be effective prospectively for reporting periods beginning on or after December 15, 2017, and early adoption is permitted for periods beginning on or after December 31, 2016. The Company is currently assessing the impact of the ASU on the Company's Condensed Consolidated Financial Statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of certain cash receipts and cash payments, which intends to reduce the diversity in practice in how certain transactions are classified on the statement of cash flows. This amendment will be effective retrospectively for reporting periods beginning after December 31, 2017, and early adoption is permitted. The Company does not expect this ASU to have a material impact on the Company's Condensed Consolidated Financial Statements.

Acquisitions & Divestitures	9 Months Ended
Acquisitions & Divestitures	Sep. 30, 2016
Business Combinations [Abstract]
Acquisitions & Divestitures [Text Block]	Acquisitions During the three months ended September 30, 2016, QEP acquired various oil and gas properties, primarily proved undeveloped leasehold acreage in the Williston Basin, for an aggregate purchase price of $16.3 million. The Company recorded a $4.4 million bargain purchase gain associated with the acquisition. The bargain purchase gain is reported on the Condensed Consolidated Statements of Operations within "Interest and other income (expense)". During the three months ended September 30, 2015, QEP acquired various oil and gas properties, primarily undeveloped leasehold acreage in the Permian Basin, for an aggregate purchase price of $24.1 million. During the nine months ended September 30, 2016, QEP acquired various oil and gas properties, primarily in the Williston and Permian basins, for an aggregate purchase price of $46.1 million, including additional interests in QEP's operated wells and additional undeveloped leasehold acreage. In conjunction with the acquisitions, the Company recorded $3.7 million of goodwill and a $4.4 million bargain purchase gain. During the nine months ended September 30, 2015, QEP acquired various oil and gas properties, primarily undeveloped leasehold acreage in the Permian Basin, for an aggregate purchase price of $23.5 million. Divestitures During the three and nine months ended September 30, 2016, QEP received proceeds of $5.2 million and $28.9 million, respectively, and recorded a pre-tax gain on sale of $5.3 million and $5.0 million, respectively, primarily related to the divestiture of certain non-core properties in Other Southern. During the three and nine months ended September 30, 2015, QEP recorded a pre-tax gain on sale of $12.9 million and $6.9 million, respectively, comprised of a gain related to divestitures and post-closing purchase price adjustments of certain non-core properties in Other Southern, partially offset by a loss recognized for post-closing adjustments related to the sale of QEP's midstream business in 2014. These gains and losses are reported on the Condensed Consolidated Statements of Operations within "Net gain (loss) from asset sales".

Earnings Per Share

9 Months Ended

Sep. 30, 2016

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 shares are included in weighted-average basic common shares outstanding because, once the shares are granted, the restricted shares are considered issued and outstanding, the historical forfeiture rate is minimal and the restricted shares 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 stock 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 stock does 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, 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 due to QEP's net loss. During the three and nine months ended September 30, 2015, there were no anti-dilutive shares.

A reconciliation of the components of basic and diluted shares used in the EPS calculation follows:



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2016	2015	2016	2015
	(in millions)
Weighted-average basic common shares outstanding	239.6	176.7	215.7	176.5
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	239.6	176.7	215.7	176.5

Asset Retirement Obligations

9 Months Ended

Sep. 30, 2016

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 $217.5 million and $206.8 million ARO liability for the periods ended September 30, 2016 and December 31, 2015, respectively, $4.4 million and $1.9 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
	2016
	(in millions)
ARO liability at January 1,	$	206.8
Accretion	6.5
Additions	3.6
Revisions	7.1
Liabilities settled	(6.5		)
ARO liability at September 30,	$	217.5

Fair Value Measurements

9 Months Ended

Sep. 30, 2016

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, 2016 and December 31, 2015, 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, 2016
	(in millions)
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	7.6	$	—	$	(7.1	)	$	0.5
Fair value of derivative contracts – long-term	—		—		—		—			—
Total financial assets	$	—	$	7.6	$	—	$	(7.1	)	$	0.5

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	41.6	$	—	$	(7.1	)	$	34.5
Fair value of derivative contracts – long-term	—		19.4		—		—			19.4
Total financial liabilities	$	—	$	61.0	$	—	$	(7.1	)	$	53.9

	December 31, 2015
	(in millions)
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	147.8	$	—	$	(1.0	)	$	146.8
Fair value of derivative contracts – long-term	—		23.2		—		—			23.2
Total financial assets	$	—	$	171.0	$	—	$	(1.0	)	$	170.0

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	1.8	$	—	$	(1.0	)	$	0.8
Fair value of derivative contracts – long-term	—		4.0		—		—			4.0
Total financial liabilities	$	—	$	5.8	$	—	$	(1.0	)	$	4.8

_______________________


⁽¹⁾	The Company nets its derivative contract assets and liabilities outstanding with the same counterparty on the Condensed Consolidated Balance Sheets, as the contracts contain netting provisions. Refer to 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 accompanying 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, 2016				December 31, 2015
	(in millions)
Financial Assets
Cash and cash equivalents	$	1,032.2	$	1,032.2	$	376.1	$	376.1
Financial Liabilities
Checks outstanding in excess of cash balances	$	4.3	$	4.3	$	29.8	$	29.8
Long-term debt	$	2,019.3	$	2,067.9	$	2,191.5	$	1,784.6

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 carrying amount of variable-rate, long-term debt approximates fair value because the floating interest rate paid on such debt was set for periods of one month.

The initial measurement of ARO at fair value is calculated using discounted cash flow techniques and based on internal estimates of future retirement costs associated with property, plant and equipment. Significant Level 3 inputs used in the calculation of asset retirement obligations include 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 nonrecurring 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, 2016 and 2015, the Company recorded impairments on certain proved oil and gas properties of $1,167.9 million and $33.8 million, respectively, 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 which 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, 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: estimated quantities of gas, oil and NGL reserves; estimates of future commodity prices; and 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.

- 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, 2016

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 gas or oil 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. Gas price derivative instruments are typically structured as fixed-price swaps or collars at regional price indices. 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. QEP also enters into crude oil and natural gas basis swaps to achieve a fixed-price swap for a portion of its gas and oil 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 and avoids 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, 2016:



Year	Index	Total Volumes	Average Swap Price per Unit
		(in millions)
Gas sales		(MMBtu)	($/MMBtu)
2016	NYMEX HH	15.6	$	2.80
2016	IFNPCR	18.4	$	2.53
2017	NYMEX HH	80.3	$	2.78
2017	IFNPCR	32.9	$	2.51
2018	NYMEX HH	29.2	$	2.92
Oil sales		(bbls)	($/bbl)
2016	NYMEX WTI	3.0	$	51.24
2017	NYMEX WTI	11.0	$	50.74
2018	NYMEX WTI	5.1	$	52.73

The following table presents QEP's volumes and average prices for its commodity derivative gas collars as of September 30, 2016:



Year	Index	Total Volumes	Average Price Floor		Average Price Ceiling
		(in millions)
		(MMBtu)	($/MMBtu)		($/MMBtu)
2016	NYMEX HH	1.8	$	2.75	$	3.89
2017	NYMEX HH	11.0	$	2.50	$	3.50

QEP uses gas basis swaps, combined with 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 gas basis swaps as of September 30, 2016:



Year	Index Less Differential	Index	Total Volumes	Weighted-Average Differential
			(in millions)
			(MMBtu)	($/MMBtu)
2016	NYMEX HH	IFNPCR	9.2	$	(0.16	)
2017	NYMEX HH	IFNPCR	51.1	$	(0.18	)
2018	NYMEX HH	IFNPCR	7.3	$	(0.16	)

Derivative Contracts – 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, 2016:



Year	Type of Contract	Index	Total Volumes	Average Swap Price per Unit
			(in millions)
Gas sales			(MMBtu)	($/MMBtu)
2016	SWAP	IFNPCR	2.0	$	2.78
2017	SWAP	IFNPCR	3.8	$	2.87
Gas purchases
2016	SWAP	IFNPCR	1.5	$	2.57

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, 2016		December 31, 2015		September 30, 2016		December 31, 2015
Current:		(in millions)
Commodity	Fair value of derivative contracts	$	7.6	$	147.8	$	41.6	$	1.8
Long-term:
Commodity	Fair value of derivative contracts	—		23.2		19.4		4.0
Total derivative instruments		$	7.6	$	171.0	$	61.0	$	5.8

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	2016			2015			2016			2015
Realized gains (losses) on commodity derivative contracts	(in millions)
Production
Gas derivative contracts	$	0.4		$	23.1		$	50.8		$	69.1
Oil derivative contracts	19.1			96.8			79.8			245.3
Storage
Gas derivative contracts	0.1			(0.1		)	2.9			2.1
Total realized gains (losses) on commodity derivative contracts	19.6			119.8			133.5			316.5
Unrealized gains (losses) on commodity derivative contracts
Production
Gas derivative contracts	24.8			3.6			(80.0		)	(19.5		)
Oil derivative contracts	(0.3		)	28.8			(135.9		)	(128.0		)
Storage
Gas derivative contracts	0.4			1.4			(2.7		)	(0.5		)
Total unrealized gains (losses) on commodity derivative contracts	24.9			33.8			(218.6		)	(148.0		)
Total realized and unrealized gains (losses) on commodity derivative contracts	$	44.5		$	153.6		$	(85.1	)	$	168.5

- 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

Restructuring Costs	9 Months Ended
Restructuring Costs	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	In April 2016, the Company streamlined its organizational structure, resulting in a reduction of approximately 6% of its total workforce. The total costs related to the 2016 restructuring were approximately $1.9 million and were related to one-time termination benefits. During the three and nine months ended September 30, 2016, restructuring costs of $0.1 million and $1.9 million, respectively, were incurred and paid related to the 2016 restructuring. The Company does not expect to incur additional costs related to the 2016 restructuring. During 2015, QEP had multiple restructuring events, including the closure of its Tulsa office, which occurred in the third quarter of 2015. The total costs related to the 2015 restructuring events were approximately $8.3 million, of which approximately $5.3 million was related to one-time termination benefits and approximately $3.0 million was related to relocation of certain employees. During the three and nine months ended September 30, 2016, restructuring costs of $0.1 million and $0.6 million, respectively, were incurred and paid related to the Tulsa office closure, all of which were related to the relocation of certain employees. The Company does not expect to incur additional costs related to the closure of its Tulsa office. All restructuring costs were recorded within "General and administrative" expense on the Condensed Consolidated Statement of Operations.

Debt

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Debt [Text Block]

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



	September 30, 2016			December 31, 2015
	(in millions)
Revolving Credit Facility due 2019	$	—		$	—
6.05% Senior Notes due 2016 ⁽¹⁾	—			176.8
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	(25.7		)	(30.3		)
Total principal amount of debt (including current portion)	2,019.3			2,191.5
Less: current portion of long-term debt	—			(176.8		)
Total long-term debt outstanding	$	2,019.3		$	2,014.7

_______________________


⁽¹⁾	During the three months ended September 30, 2016, the Company paid $176.8 million for the repayment of the 6.05% Senior Notes, which were due on September 1, 2016.

Of the total debt outstanding on September 30, 2016, 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 provisions and restrictions. The credit agreement contains financial covenants (as defined in the credit agreement) that limit the amount of debt the Company may 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, and 3.75 times thereafter and (iii) a present value coverage ratio under which 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. At September 30, 2016, QEP was in compliance with the covenants under the credit agreement.

During the nine months ended September 30, 2016 and 2015, QEP had no borrowings under the credit facility. Additionally, as of September 30, 2016 and December 31, 2015, QEP had no borrowings outstanding under the credit facility and had $2.8 million and $3.4 million, respectively, in letters of credit outstanding under the credit facility.

Senior Notes

At September 30, 2016, 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 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, 2016
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 judgments 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. Rocky Mountain Resources Lawsuit – Rocky Mountain Resources, LLC (Rocky Mountain) filed a complaint against the Company in March 2011, seeking determination of the existence of a 4% overriding royalty interest in an oil and gas lease. Rocky Mountain alleges that the defendants have failed to pay Rocky Mountain monies associated with the claimed 4% overriding royalty interest since the issuance of the lease by the State of Wyoming in 1980. In February 2015, a jury rendered a verdict against the Company and awarded Rocky Mountain damages in the amount of $16.7 million, including interest. The Company appealed the verdict to the Wyoming Supreme Court and posted a bond for approximately $20.0 million (representing the amount of the verdict and two years of accrued interest at the statutory rate of 10%). In accordance with the Court’s order, the Company is depositing the future monthly revenues attributable to the 4% overriding royalty interest with the Court as such amounts become due and payable. These deposits are presented within “Prepaid expenses and other” on the Company’s Condensed Consolidated Balance Sheets. The overriding royalty payments will be subject to the direction of the Court following the conclusion of the appeal. Claims of Former Limited Partners – The Company received a demand from certain former limited partners of terminated drilling partnerships of the Company (acting as the general partner). The former limited partners allege that distributions to which they were entitled from the drilling partnerships were not made or were calculated incorrectly. Other former limited partners may assert claims. No litigation has been filed, and the Company is in the process of evaluating the allegations and its defenses. Arbitration Regarding Gas Purchase Agreement – A midstream service provider that purchases, gathers and processes natural gas produced from oil wells operated by the Company in the Williston Basin has claimed that the decline in commodity prices has rendered its gathering and processing operations “uneconomic” and demanded that, effective March 1, 2016, QEP pay additional fees for gathering and processing services. The midstream service provider has been unwilling to connect new wells unless the Company agrees to pay the increased fees for production from the new wells. QEP initiated arbitration proceedings in May 2016 to enforce the terms of the existing agreement. The arbitration proceedings are scheduled for the fourth quarter of 2016. Department of Interior Investigation regarding Indian Royalties – Pursuant to regulations published by the Office of Natural Resources Revenue (ONRR) of the Department of the Interior (DOI), certain of the Company’s Indian leases are subject to “dual accounting” and “major portion” requirements. The Company must initially report royalties on production from these leases based upon its actual sales arrangements and, once ONRR publishes the major portion price (approximately 18 months after a calendar year), the Company must recalculate its previously reported royalties for the applicable calendar year and pay additional royalties if the dual accounting or major portion pricing results in higher royalties. In July 2016, the Company was notified that the Office of Inspector General of the DOI is conducting an investigation into the timeliness of the Company’s compliance with ONRR dual accounting and major portion requirements to recalculate royalties for 2013 on production from certain Indian leases. There may be penalties and additional royalties due. 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. In addition, since February 2016, the North Dakota Department of Health (NDDH) has engaged with the oil and gas production industry in North Dakota to address potential noncompliance associated with emissions from tank batteries. QEP has participated in these discussions. While no formal federal or state enforcement action has been commenced in connection with the tank batteries to date, other operators have been assessed penalties following similar information requests. QEP anticipates that resolution of these matters will likely result in penalties and require QEP to incur additional capital expenditures to correct noncompliance issues. To the extent that the Company can reasonably estimate losses for contingencies where the risk of a material loss (in excess of accruals, if any) is reasonably possible, the Company estimates such losses could total between zero and approximately $60.0 million.

Share-Based Compensation

9 Months Ended

Sep. 30, 2016

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

Share-Based Compensation [Text Block]

QEP issues stock options, restricted shares 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 shares, restricted share units and performance share units. There were 7.1 million shares available for future grants under the LTSIP at September 30, 2016.

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,
	2016		2015		2016		2015
	(in millions)
Stock options	$	0.6	$	0.7	$	1.8	$	2.2
Restricted share awards	6.0		6.8		18.2		19.5
Performance share units	3.2		0.2		8.8		1.6
Restricted share units	0.1		—		0.2		—
Total share-based compensation expense	$	9.9	$	7.7	$	29.0	$	23.3

Stock Options

QEP uses the Black-Scholes-Merton mathematical model to estimate the fair value of stock option awards at the date of the 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 options granted and major assumptions used in the model at the date of grant are listed below for the nine months ended September 30, 2016:



	Stock Option Assumptions
Weighted-average grant date fair value of awards granted during the period	$	3.77
Weighted-average risk-free interest rate	1.15		%
Weighted-average expected price volatility	43.4		%
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, 2015	2,200,776		$	27.94
Granted	438,180		10.14
Canceled	(486,999	)	23.77
Outstanding at September 30, 2016	2,151,957		$	25.26	3.92	$	4.1
Options Exercisable at September 30, 2016	1,385,753		$	30.18	2.86	$	0.2
Unvested Options at September 30, 2016	766,204		$	16.38	5.83	$	3.9

During the nine months ended September 30, 2016, there were no exercises of stock options. During the nine months ended September 30, 2015, the total intrinsic value (the difference between the market price at the exercise date and the exercise price) of options exercised was $0.1 million. As of September 30, 2016, $1.7 million of unrecognized compensation cost related to stock options granted under the LTSIP, which is included within "Additional paid-in capital" on the Condensed Consolidated Balance Sheet, is expected to be recognized over a weighted-average period of 2.02 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, 2016 and 2015, was $24.2 million and $21.0 million, respectively. The weighted-average grant date fair value of restricted share awards was $10.37 per share and $21.02 per share for the nine months ended September 30, 2016 and 2015, respectively. As of September 30, 2016, $22.9 million of unrecognized compensation cost related to restricted share awards granted under the LTSIP, which is included within "Additional paid-in capital" on the Condensed Consolidated Balance Sheet, is expected to be recognized over a weighted-average vesting period of 2.15 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, 2015	2,008,210		$	24.18
Granted	2,427,634		10.37
Vested	(966,748	)	25.03
Forfeited	(252,448	)	14.16
Unvested balance at September 30, 2016	3,216,648		$	14.29

Performance Share Units

The performance share units' cash payouts 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, 2016, 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 Sheet. 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 $10.16 per share and $21.69 per share for the nine months ended September 30, 2016 and 2015, respectively. As of September 30, 2016, $16.6 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 1.98 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, 2015	630,786		$	27.50
Granted	597,185		10.16
Vested and Paid	(178,169	)	30.07
Forfeited	(22,431	)	15.09
Unvested balance at September 30, 2016	1,027,371		$	17.24

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 classified as liabilities and are included within "Other long-term liabilities" on the Condensed Consolidated Balance Sheet. As these awards are dependent upon the Company's stock price, they are remeasured at fair value at the end of each reporting period. The weighted-average grant date fair value of the restricted share units was $10.12 per share for the nine months ended September 30, 2016. As of September 30, 2016, $0.2 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 2.59 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, 2015	—		$	—
Granted	21,493		10.12
Vested	(193	)	10.12
Forfeited	(3,266	)	10.12
Unvested balance at September 30, 2016	18,034		$	10.12

- 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, 2016

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, 2016, 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 2016. Contributions to the Pension Plan increase plan assets.

As a result of the Company's divestitures in 2014 and retirements in 2015, the number of active participants in the Pension Plan fell to 50 employees during the year ended December 31, 2015, which is the minimum number of active participants required for a plan to be qualified under the Internal Revenue Services' participation rules. In order to prevent disqualification, 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, 2016, the Company made contributions of $3.5 million to its SERP and expects to contribute an additional $0.1 million to its SERP during the remainder of 2016. 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.

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, 2016, 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 2016. Contributions to the Medical Plan are used to fund current benefit payments.

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,
	2016			2015			2016			2015
Pension Plan and SERP benefits	(in millions)
Service cost	$	0.3		$	0.5		$	0.9		$	1.5
Interest cost	1.3			1.3			3.9			3.7
Expected return on plan assets	(1.4		)	(1.5		)	(4.2		)	(4.3		)
Amortization of prior service costs ⁽¹⁾	0.3			0.4			0.9			1.3
Amortization of actuarial losses ⁽¹⁾	0.2			0.1			0.6			0.4
Curtailment loss ⁽²⁾	—			—			—			11.2
Periodic expense	$	0.7		$	0.8		$	2.1		$	13.8

Medical Plan benefits
Interest cost	$	0.1		$	0.1		$	0.2		$	0.2
Amortization of prior service costs ⁽¹⁾	—			—			0.1			0.1
Periodic expense	$	0.1		$	0.1		$	0.3		$	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 "General and administrative" 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 are recognized on the Condensed Consolidated Statements of Operations within "General and administrative" expense for the nine months ended September 30, 2015.

Subsequent Event (Notes)	9 Months Ended
Subsequent Event (Notes)	Sep. 30, 2016
Subsequent Event [Line Items]
Subsequent Events [Text Block]	On October 19, 2016, QEP closed on its previously announced acquisition of oil and gas properties in the Permian Basin for an aggregate purchase price of approximately $590.0 million, subject to customary purchase price adjustments (the 2016 Permian Acquisition). The 2016 Permian Acquisition consists of approximately 9,400 net acres in Martin County, Texas, which are primarily held by production from existing vertical wells. The 2016 Permian Acquisition was funded with proceeds from the June 2016 equity offering and cash on hand. Final purchase accounting for the transaction was not complete at the time this Form 10-Q was filed with the SEC, and as such, certain disclosures required by ASC Topic 805, Business Combinations, have not been made herein. The Company will include this information in its 2016 Annual Report on Form 10-K.

Basis of Presentation Revision of Financial Statements (Tables)

9 Months Ended

Sep. 30, 2015

Error Corrections and Prior Period Adjustments Restatement [Line Items]

Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]



	Three Months Ended							Nine Months Ended
	September 30, 2015							September 30, 2015
	As reported		As revised		Change			As reported		As revised		Change
REVENUES	(in millions)
Purchased gas and oil sales	$	176.3	$	147.2	$	(29.1	)	$	558.6	$	472.0	$	(86.6	)
Total Revenues	536.7		507.6		(29.1		)	1,636.9		1,550.3		(86.6		)
OPERATING EXPENSES
Purchased gas and oil expense	$	175.1	$	146.0	$	(29.1	)	$	561.7	$	475.1	$	(86.6	)
Total Operating Expenses	637.3		608.2		(29.1		)	1,876.8		1,790.2		(86.6		)

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2016

Earnings Per Share [Abstract]

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

A reconciliation of the components of basic and diluted shares used in the EPS calculation follows:



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2016	2015	2016	2015
	(in millions)
Weighted-average basic common shares outstanding	239.6	176.7	215.7	176.5
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	239.6	176.7	215.7	176.5

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2016

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, 2016 and December 31, 2015, 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, 2016
	(in millions)
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	7.6	$	—	$	(7.1	)	$	0.5
Fair value of derivative contracts – long-term	—		—		—		—			—
Total financial assets	$	—	$	7.6	$	—	$	(7.1	)	$	0.5

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	41.6	$	—	$	(7.1	)	$	34.5
Fair value of derivative contracts – long-term	—		19.4		—		—			19.4
Total financial liabilities	$	—	$	61.0	$	—	$	(7.1	)	$	53.9

	December 31, 2015
	(in millions)
Financial Assets
Fair value of derivative contracts – short-term	$	—	$	147.8	$	—	$	(1.0	)	$	146.8
Fair value of derivative contracts – long-term	—		23.2		—		—			23.2
Total financial assets	$	—	$	171.0	$	—	$	(1.0	)	$	170.0

Financial Liabilities
Fair value of derivative contracts – short-term	$	—	$	1.8	$	—	$	(1.0	)	$	0.8
Fair value of derivative contracts – long-term	—		4.0		—		—			4.0
Total financial liabilities	$	—	$	5.8	$	—	$	(1.0	)	$	4.8

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, 2016				December 31, 2015
	(in millions)
Financial Assets
Cash and cash equivalents	$	1,032.2	$	1,032.2	$	376.1	$	376.1
Financial Liabilities
Checks outstanding in excess of cash balances	$	4.3	$	4.3	$	29.8	$	29.8
Long-term debt	$	2,019.3	$	2,067.9	$	2,191.5	$	1,784.6

- 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, 2016

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, 2016:



Year	Index	Total Volumes	Average Swap Price per Unit
		(in millions)
Gas sales		(MMBtu)	($/MMBtu)
2016	NYMEX HH	15.6	$	2.80
2016	IFNPCR	18.4	$	2.53
2017	NYMEX HH	80.3	$	2.78
2017	IFNPCR	32.9	$	2.51
2018	NYMEX HH	29.2	$	2.92
Oil sales		(bbls)	($/bbl)
2016	NYMEX WTI	3.0	$	51.24
2017	NYMEX WTI	11.0	$	50.74
2018	NYMEX WTI	5.1	$	52.73

The following table presents QEP's volumes and average prices for its commodity derivative gas collars as of September 30, 2016:



Year	Index	Total Volumes	Average Price Floor		Average Price Ceiling
		(in millions)
		(MMBtu)	($/MMBtu)		($/MMBtu)
2016	NYMEX HH	1.8	$	2.75	$	3.89
2017	NYMEX HH	11.0	$	2.50	$	3.50



Year	Index Less Differential	Index	Total Volumes	Weighted-Average Differential
			(in millions)
			(MMBtu)	($/MMBtu)
2016	NYMEX HH	IFNPCR	9.2	$	(0.16	)
2017	NYMEX HH	IFNPCR	51.1	$	(0.18	)
2018	NYMEX HH	IFNPCR	7.3	$	(0.16	)

Derivative Contracts – Storage



Year	Type of Contract	Index	Total Volumes	Average Swap Price per Unit
			(in millions)
Gas sales			(MMBtu)	($/MMBtu)
2016	SWAP	IFNPCR	2.0	$	2.78
2017	SWAP	IFNPCR	3.8	$	2.87
Gas purchases
2016	SWAP	IFNPCR	1.5	$	2.57

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, 2016		December 31, 2015		September 30, 2016		December 31, 2015
Current:		(in millions)
Commodity	Fair value of derivative contracts	$	7.6	$	147.8	$	41.6	$	1.8
Long-term:
Commodity	Fair value of derivative contracts	—		23.2		19.4		4.0
Total derivative instruments		$	7.6	$	171.0	$	61.0	$	5.8

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	2016			2015			2016			2015
Realized gains (losses) on commodity derivative contracts	(in millions)
Production
Gas derivative contracts	$	0.4		$	23.1		$	50.8		$	69.1
Oil derivative contracts	19.1			96.8			79.8			245.3
Storage
Gas derivative contracts	0.1			(0.1		)	2.9			2.1
Total realized gains (losses) on commodity derivative contracts	19.6			119.8			133.5			316.5
Unrealized gains (losses) on commodity derivative contracts
Production
Gas derivative contracts	24.8			3.6			(80.0		)	(19.5		)
Oil derivative contracts	(0.3		)	28.8			(135.9		)	(128.0		)
Storage
Gas derivative contracts	0.4			1.4			(2.7		)	(0.5		)
Total unrealized gains (losses) on commodity derivative contracts	24.9			33.8			(218.6		)	(148.0		)
Total realized and unrealized gains (losses) on commodity derivative contracts	$	44.5		$	153.6		$	(85.1	)	$	168.5

Debt (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Debt Outstanding [Table Text Block]

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



	September 30, 2016			December 31, 2015
	(in millions)
Revolving Credit Facility due 2019	$	—		$	—
6.05% Senior Notes due 2016 ⁽¹⁾	—			176.8
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	(25.7		)	(30.3		)
Total principal amount of debt (including current portion)	2,019.3			2,191.5
Less: current portion of long-term debt	—			(176.8		)
Total long-term debt outstanding	$	2,019.3		$	2,014.7

Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

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,
	2016		2015		2016		2015
	(in millions)
Stock options	$	0.6	$	0.7	$	1.8	$	2.2
Restricted share awards	6.0		6.8		18.2		19.5
Performance share units	3.2		0.2		8.8		1.6
Restricted share units	0.1		—		0.2		—
Total share-based compensation expense	$	9.9	$	7.7	$	29.0	$	23.3

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

The calculated fair value of options granted and major assumptions used in the model at the date of grant are listed below for the nine months ended September 30, 2016:



	Stock Option Assumptions
Weighted-average grant date fair value of awards granted during the period	$	3.77
Weighted-average risk-free interest rate	1.15		%
Weighted-average expected price volatility	43.4		%
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, 2015	2,200,776		$	27.94
Granted	438,180		10.14
Canceled	(486,999	)	23.77
Outstanding at September 30, 2016	2,151,957		$	25.26	3.92	$	4.1
Options Exercisable at September 30, 2016	1,385,753		$	30.18	2.86	$	0.2
Unvested Options at September 30, 2016	766,204		$	16.38	5.83	$	3.9

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



	Restricted Share Units Outstanding		Weighted-Average Grant Date Fair Value
			(per share)
Unvested balance at December 31, 2015	—		$	—
Granted	21,493		10.12
Vested	(193	)	10.12
Forfeited	(3,266	)	10.12
Unvested balance at September 30, 2016	18,034		$	10.12

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, 2015	2,008,210		$	24.18
Granted	2,427,634		10.37
Vested	(966,748	)	25.03
Forfeited	(252,448	)	14.16
Unvested balance at September 30, 2016	3,216,648		$	14.29

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, 2015	630,786		$	27.50
Granted	597,185		10.16
Vested and Paid	(178,169	)	30.07
Forfeited	(22,431	)	15.09
Unvested balance at September 30, 2016	1,027,371		$	17.24

Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2016

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,
	2016			2015			2016			2015
Pension Plan and SERP benefits	(in millions)
Service cost	$	0.3		$	0.5		$	0.9		$	1.5
Interest cost	1.3			1.3			3.9			3.7
Expected return on plan assets	(1.4		)	(1.5		)	(4.2		)	(4.3		)
Amortization of prior service costs ⁽¹⁾	0.3			0.4			0.9			1.3
Amortization of actuarial losses ⁽¹⁾	0.2			0.1			0.6			0.4
Curtailment loss ⁽²⁾	—			—			—			11.2
Periodic expense	$	0.7		$	0.8		$	2.1		$	13.8

Medical Plan benefits
Interest cost	$	0.1		$	0.1		$	0.2		$	0.2
Amortization of prior service costs ⁽¹⁾	—			—			0.1			0.1
Periodic expense	$	0.1		$	0.1		$	0.3		$	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 "General and administrative" 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 are recognized on the Condensed Consolidated Statements of Operations within "General and administrative" expense for the nine months ended September 30, 2015

Basis of Presentation Equity Offering (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Schedule of Stock Issuance [Line Items]
Proceeds from Issuance of Common Stock			$ 781.6	$ 0.0
Share Issuance - June 2016 [Domain]
Schedule of Stock Issuance [Line Items]
Common Stock, Shares Issued in Period	23,000
Proceeds from Issuance of Common Stock	$ 413.0
Share Issuance - March 2016 [Domain]
Schedule of Stock Issuance [Line Items]
Common Stock, Shares Issued in Period		37,950
Proceeds from Issuance of Common Stock		$ 368.6

Basis of Presentation Revision of Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revision of Financial Statements [Line Items]
Operating Expenses	$ 481.3	$ 608.2	$ 2,548.1	$ 1,790.2
As reported [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		176.3		558.6
Revenues		536.7		1,636.9
Cost of Purchased Oil and Gas		175.1		561.7
Operating Expenses		637.3		1,876.8
As revised [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		147.2		472.0
Revenues		507.6		1,550.3
Cost of Purchased Oil and Gas		146.0		475.1
Operating Expenses		608.2		1,790.2
Change [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		(29.1)		(86.6)
Revenues		(29.1)		(86.6)
Cost of Purchased Oil and Gas		(29.1)		(86.6)
Operating Expenses		$ (29.1)		$ (86.6)

Basis of Presentation Impairment of Long-Lived Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment	$ 5.0	$ 15.0	$ 1,188.2	$ 35.5
Goodwill, Acquired During Period			3.7
Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			1,167.9	$ 33.8
Unproved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			16.6
Pinedale [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			1,164.0
Other Northern [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			3.5
Other Southern [Member] \| Proved Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			0.4
Williston & Permian Basins [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill, Acquired During Period			$ 3.7

Acquisitions & Divestitures (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) a	Sep. 30, 2015 USD ($)
Business Combinations [Abstract]
Proceeds from Sale of Oil and Gas Property and Equipment	$ 5.2		$ 28.9	$ 5.2
Net gain (loss) from asset sales	5.3	$ 12.9	5.0	6.9
Business Acquisition [Line Items]
Acquisition Costs, Period Cost	16.3	$ 24.1	46.1	23.5
Bargain purchase gain from acquisition	$ 4.4		4.4	$ 0.0
Goodwill, Acquired During Period			3.7
Permian Basin Acquisition [Member]
Business Acquisition [Line Items]
Acquisition Costs, Period Cost			$ 590.0
Net Acres \| a			9,400
Williston & Permian Basins [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period			$ 3.7

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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Anti-dilutive shares	0.2		0.1
Weighted-average basic common shares outstanding	239.6	176.7	215.7	176.5
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	239.6	176.7	215.7	176.5

Capitalized Exploratory Well Costs (Details) $ in Millions	9 Months Ended
Capitalized Exploratory Well Costs (Details) $ in Millions	Sep. 30, 2016 USD ($)
Capitalized Exploratory Well Costs [Abstract]
Capitalized exploratory well costs, beginning balance	$ 2.6
Additions to capitalized exploratory well costs pending the determination of proved reserves	11.0
Reclassification to proved properties after the determination of proved reserves	0.0
Capitalized exploratory well costs charged to expense	(0.1)
Capitalized exploratory well costs, ending balance	$ 13.5

Asset Retirement Obligations (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Asset Retirement Obligation [Abstract]
Asset Retirement Obligation, Current	$ 4.4	$ 1.9
ARO Liability [Roll Forward]
ARO liability, Beginning Balance	206.8
Accretion	6.5
Additions	3.6
Asset Retirement Obligation, Revision of Estimate	7.1
Liabilities settled	(6.5)
ARO liability, Ending Balance	$ 217.5

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

9 Months Ended

Sep. 30, 2016

Sep. 30, 2015

Dec. 31, 2015

Financial Assets

Net amount of derivative assets presented on condensed consolidated balance sheets

$ 0.5

$ 170.0

Financial liabilities

Net amount of derivative liabilities presented on condensed consolidated balance sheets

53.9

4.8

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

7.6

171.0

Financial liabilities

Derivative Liability, Fair Value, Gross

61.0

5.8

Level 3 [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Netting Adjustments [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

^[1]

(7.1)

(1.0)

Financial liabilities

Derivative Liability, Fair Value, Gross

^[1]

(7.1)

(1.0)

Long-term [Member]

Financial Assets

Net amount of derivative assets presented on condensed consolidated balance sheets

23.2

Financial liabilities

Net amount of derivative liabilities presented on condensed consolidated balance sheets

19.4

4.0

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

23.2

Financial liabilities

Derivative Liability, Fair Value, Gross

19.4

4.0

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

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Long-term [Member] | Netting Adjustments [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

^[1]

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

^[1]

0.0

Short-term [Member]

Financial Assets

Net amount of derivative assets presented on condensed consolidated balance sheets

0.5

146.8

Financial liabilities

Net amount of derivative liabilities presented on condensed consolidated balance sheets

34.5

0.8

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

7.6

147.8

Financial liabilities

Derivative Liability, Fair Value, Gross

41.6

1.8

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

Financial Assets

Derivative Asset, Fair Value, Gross

0.0

Financial liabilities

Derivative Liability, Fair Value, Gross

0.0

Short-term [Member] | Netting Adjustments [Member]

Financial Assets

Derivative Asset, Fair Value, Gross

^[1]

(7.1)

(1.0)

Financial liabilities

Derivative Liability, Fair Value, Gross

^[1]

(7.1)

$ (1.0)

Proved Property [Member]

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

Impairment of Oil and Gas Properties

$ 1,167.9

$ 33.8

[1]

The Company nets its derivative contract assets and liabilities outstanding with the same counterparty on the Condensed Consolidated Balance Sheets, as the contracts contain netting provisions. Refer to 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, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 1,032.2	$ 376.1	$ 495.8	$ 1,160.1
Checks outstanding in excess of cash balances	4.3	29.8
Long-term debt	2,019.3	2,191.5
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	1,032.2	376.1
Checks outstanding in excess of cash balances	4.3	29.8
Long-term debt	2,019.3	2,191.5
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, at Carrying Value	1,032.2	376.1
Checks outstanding in excess of cash balances	4.3	29.8
Long-term debt, fair value	$ 2,067.9	$ 1,784.6

Derivative Contracts (Narrative) (Details)	9 Months Ended
Derivative Contracts (Narrative) (Details)	Sep. 30, 2016
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, 2016 USD ($) MMBTU $ / MMBTU
Gas Swaps [Member] \| Production [Member] \| Year 2016 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	15.6
Average Swap Price per Unit \| $	$ 2.80
Gas Swaps [Member] \| Production [Member] \| Year 2016 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	18.4
Average Swap Price per Unit \| $	$ 2.53
Gas Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	80.3
Average Swap Price per Unit \| $	$ 2.78
Gas Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	32.9
Average Swap Price per Unit \| $	$ 2.51
Gas Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	29.2
Average Swap Price per Unit \| $	$ 2.92
Gas Swaps [Member] \| Storage [Member] \| Year 2016 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	2.0
Average Swap Price per Unit \| $	$ 2.78
Gas Swaps [Member] \| Storage [Member] \| Year 2017 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	3.8
Average Swap Price per Unit \| $	$ 2.87
Oil Swaps [Member] \| Production [Member] \| Year 2016 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	3.0
Average Swap Price per Unit \| $	$ 51.24
Oil Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	11.0
Average Swap Price per Unit \| $	$ 50.74
Oil Swaps [Member] \| Production [Member] \| Year 2018 [Member] \| NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	5.1
Average Swap Price per Unit \| $	$ 52.73
Gas Collars [Member] \| Production [Member] \| Year 2016 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	1.8
Derivative Average Price Floor \| $	$ 2.75
Derivative Average Price Ceiling \| $	$ 3.89
Gas Collars [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX HH [Member]
Derivative [Line Items]
Derivative Volumes	11.0
Derivative Average Price Floor \| $	$ 2.50
Derivative Average Price Ceiling \| $	$ 3.50
Gas Basis Swaps [Member] \| Production [Member] \| Year 2016 [Member] \| NYMEX HH LESS IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	9.2
Weighted-Average Differential \| $ / MMBTU	(0.16)
Gas Basis Swaps [Member] \| Production [Member] \| Year 2017 [Member] \| NYMEX HH LESS IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	51.1
Weighted-Average Differential \| $ / MMBTU	(0.18)
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 2016 [Member] \| IFNPCR [Member]
Derivative [Line Items]
Derivative Volumes	1.5
Average Swap Price per Unit \| $	$ 2.57

Derivative Contracts Schedule of Derivatives Financial Statement Presentation (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 7.6	$ 171.0
Derivative Liability, Fair Value, Gross	61.0	5.8
Short-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7.6	147.8
Derivative Liability, Fair Value, Gross	41.6	1.8
Long-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		23.2
Derivative Liability, Fair Value, Gross	19.4	4.0
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7.6	171.0
Derivative Liability, Fair Value, Gross	61.0	5.8
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member] \| Short-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7.6	147.8
Derivative Liability, Fair Value, Gross	41.6	1.8
Fair Value, Measurements, Recurring [Member] \| Commodity Contract [Member] \| Long-term [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.0	23.2
Derivative Liability, Fair Value, Gross	$ 19.4	$ 4.0

Derivative Contracts Gain (Loss) in Statement of Financial Performance (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments	$ 19.6	$ 119.8	$ 133.5	$ 316.5
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments	24.9	33.8	(218.6)	(148.0)
Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments	44.5	153.6	(85.1)	168.5
Oil derivative contracts [Member] \| Production [Member]
Derivative [Line Items]
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments	19.1	96.8	79.8	245.3
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments	(0.3)	28.8	(135.9)	(128.0)
Natural gas derivative contracts [Member] \| Production [Member]
Derivative [Line Items]
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments	0.4	23.1	50.8	69.1
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments	24.8	3.6	(80.0)	(19.5)
Natural gas derivative contracts [Member] \| Storage [Member]
Derivative [Line Items]
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments	0.1	(0.1)	2.9	2.1
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments	$ 0.4	$ 1.4	$ (2.7)	$ (0.5)

Restructuring Costs Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Denver Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Reduction of Employees - Restructuring	6.00%	6.00%
Restructuring and Related Cost, Expected Cost	$ 1.9	$ 1.9
Denver Restructuring [Member] \| One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.1	1.9
Tulsa Regional Office [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost			$ 8.3
Tulsa Regional Office [Member] \| One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost			5.3
Tulsa Regional Office [Member] \| Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost			$ 3.0
Restructuring and Related Cost, Incurred Cost	$ 0.1	$ 0.6

Debt (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Debt (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
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	2.8	3.4
6.05% Senior Notes due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0.0	176.8
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, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Less unamortized discount	$ (25.7)	$ (30.3)
Long-term debt	2,019.3	2,191.5
Less: current portion of long-term debt	0.0	(176.8)
Total long-term debt outstanding	2,019.3	2,014.7
Revolving Credit Facility due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0.0	0.0
Senior Notes Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0.0	176.8
Senior Notes Due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	134.0	134.0
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
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

Commitments and Contingencies (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($)
Loss Contingencies [Line Items]
Overriding Royalty Interest	4.00%
Loss on Contingency, Estimate of Possible Loss, Minimum	$ 0.0
Loss Contingency, Estimate of Possible Loss, Maximum	60.0
Rocky Mountain Resources Lawsuit [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount	$ 16.7
Litigation Settlement Statutory Interest Rate	10.00%
Loss Contingency Bond Posted	$ 20.0

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants	7.1
Share-based compensation	$ 29.0	$ 23.3
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 0.1
Unrecognized compensation costs	$ 1.7
Weighted average period for recognition of equity-based compensation expense	2 years 9 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 10.37	$ 21.02
Unrecognized compensation costs	$ 22.9
Weighted average period for recognition of equity-based compensation expense	2 years 1 month 25 days
Award vesting period	3 years
Total fair value of stock that vested during the period	$ 24.2	$ 21.0
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 10.16	$ 21.69
Unrecognized compensation costs	$ 16.6
Weighted average period for recognition of equity-based compensation expense	1 year 11 months 23 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value, grants	$ 10.12
Unrecognized compensation costs	$ 0.2
Weighted average period for recognition of equity-based compensation expense	2 years 7 months 3 days

Share-Based Compensation Share-based compensation expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 9.9	$ 7.7	$ 29.0	$ 23.3
Employee Stock Option [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	0.6	0.7	1.8	2.2
Restricted Stock [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	6.0	6.8	18.2	19.5
Performance Share Units [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	3.2	0.2	8.8	1.6
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 0.1	$ 0.0	$ 0.2	$ 0.0

Share-Based Compensation Fair Value Of Options Granted And Major Assumptions Used (Details)	9 Months Ended
	Sep. 30, 2016 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of awards granted during the period	$ 3.77
Weighted-average risk-free interest rate	1.15%
Weighted-average expected price volatility	43.40%
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, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period \| shares	2,200,776
Options granted \| shares	438,180
Options cancelled \| shares	(486,999)
Outstanding at end of period \| shares	2,151,957
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average exercise price, beginning of year \| $ / shares	$ 27.94
Weighted average exercise price, granted in period \| $ / shares	10.14
Weighted average exercise price, canceled in period \| $ / shares	23.77
Weighted average exercise price, end of year \| $ / shares	$ 25.26
Options exercisable, shares \| shares	1,385,753
Options exercisable, weighted average exercise price \| $ / shares	$ 30.18
Unvested options, shares \| shares	766,204
Unvested options, weighted average exercise price \| $ / shares	$ 16.38
Weighted average remaining contractual term, options outstanding	3 years 11 months
Weighted average remaining contractual term, options exercisable	2 years 10 months 10 days
Weighted average remaining contractual term, options unvested	5 years 10 months
Aggregate intrinsic value, options outstanding \| $	$ 4.1
Aggregate intrinsic value, options exercisable \| $	0.2
Aggregate intrinsic value, options unvested \| $	$ 3.9

Share-Based Compensation Schedule of Restricted Share Awards Transactions (Details) - Restricted Stock [Member] - $ / shares	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
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	2,008,210
Shares granted	2,427,634
Shares vested	(966,748)
Shares forfeited	(252,448)
Unvested balance at end of period	3,216,648
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	$ 24.18
Weighted average grant date fair value, grants	10.37	$ 21.02
Weighted average grant date fair value, vested	25.03
Weighted average grant date fair value, forfeited	14.16
Weighted average grant date fair value, end of period	$ 14.29

Share-Based Compensation Schedule Of Performance Share Unit Transactions (Details) - Performance Share Units [Member] - $ / shares	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
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	630,786
Shares granted	597,185
Shares vested	(178,169)
Shares forfeited	(22,431)
Unvested balance at end of period	1,027,371
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	$ 27.50
Weighted average grant date fair value, grants	10.16	$ 21.69
Weighted average grant date fair value, vested	30.07
Weighted average grant date fair value, forfeited	15.09
Weighted average grant date fair value, end of period	$ 17.24

Share-Based Compensation Schedule of Restricted Share Unit Transactions (Details) - Restricted Stock Units (RSUs) [Member]	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested balance at beginning of period \| shares	0
Weighted average grant date fair value, beginning of period \| $ / shares	$ 0.00
Shares granted \| shares	21,493
Weighted average grant date fair value, grants \| $ / shares	$ 10.12
Shares vested \| shares	(193)
Weighted average grant date fair value, vested \| $ / shares	$ 10.12
Shares forfeited \| shares	(3,266)
Weighted average grant date fair value, forfeited \| $ / shares	$ 10.12
Unvested balance at end of period \| shares	18,034
Weighted average grant date fair value, end of period \| $ / shares	$ 10.12

Employee Benefits (Narrative) (Details) $ in Millions	9 Months Ended
Employee Benefits (Narrative) (Details) $ in Millions	Sep. 30, 2016 USD ($)
Funded Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension Contributions	$ 4.0
Unfunded Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension Contributions	3.5
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	0.1
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	0.1
Other Postretirement Benefits Payments	$ 0.2

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

3 Months Ended

9 Months Ended

Sep. 30, 2016

Sep. 30, 2015

Sep. 30, 2016

Sep. 30, 2015

Pension Plan [Member]

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

Service cost

$ 0.3

$ 0.5

$ 0.9

$ 1.5

Interest cost

1.3

3.9

3.7

Expected return on plan assets

(1.4)

(1.5)

(4.2)

(4.3)

Amortization of prior service costs

^[1]

0.3

0.4

0.9

1.3

Amortization of actuarial losses

^[1]

0.2

0.1

0.6

0.4

Curtailment loss

^[2]

0.0

11.2

Periodic expense

0.7

0.8

2.1

13.8

Other Postretirement Benefit Plan [Member]

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

Interest cost

0.1

0.2

Amortization of prior service costs

^[1]

0.0

0.1

Periodic expense

$ 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 "General and administrative" 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 are recognized on the Condensed Consolidated Statements of Operations within "General and administrative" expense for the nine months ended September 30, 2015.

Subsequent Event (Details) $ in Millions	3 Months Ended		9 Months Ended
Subsequent Event (Details) $ in Millions	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) a	Sep. 30, 2015 USD ($)
Subsequent Event [Line Items]
Acquisition Costs, Period Cost	$ 16.3	$ 24.1	$ 46.1	$ 23.5
Permian Basin Acquisition [Member]
Subsequent Event [Line Items]
Acquisition Costs, Period Cost			$ 590.0
Net Acres \| a			9,400