Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]
Fair Value Disclosures [Text Block]
Retirement Benefits [Abstract]
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table]
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table]
Restructuring Type [Axis]
Restructuring Type [Axis]
Type of Restructuring [Domain]
Type of Restructuring [Domain]
Total [Member]
Total [Member]
Total [Member]
Interest and other income (expense) [Member]
Interest Income [Member]
Net gain (loss) from asset sales [Member]
Net gain (loss) from asset sales [Member]
Net gain (loss) from asset sales [Member]
Retirement Plan Type [Axis]
Retirement Plan Type [Axis]
Retirement Plan Type [Domain]
Retirement Plan Type [Domain]
Pension Plan [Member]
Pension Plan [Member]
SERP [Member]
SERP [Member]
SERP [Member]
Medical Plan [Member]
Medical Plan [Member]
Medical Plan [Member]
401(k) Plan [Member]
401(k) Plan [Member]
401(k) Plan [Member]
Pension Plan Discretionary Contribution [Member]
Pension Plan Discretionary Contribution [Member]
Pension Plan Discretionary Contribution [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by Employer
Defined Benefit Plan, Plan Assets, Contributions by Employer
Estimated Future Employer Contributions in Current Fiscal Year
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year
Pension curtailment
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment
Pension and Medical Plan curtailment
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment
Fair Value Measurements, Recurring and Nonrecurring [Table]
Fair Value Measurements, Recurring and Nonrecurring [Table]
Measurement Frequency [Axis]
Measurement Frequency [Axis]
Fair Value, Measurement Frequency [Domain]
Fair Value, Measurement Frequency [Domain]
Fair Value, Hierarchy [Axis]
Fair Value, Hierarchy [Axis]
Fair Value Hierarchy [Domain]
Fair Value Hierarchy [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of financial assets and liabilities [Table Text Block]
Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]
Fair value and related carrying amount of certain financial instruments [Table Text Block]
Fair Value, by Balance Sheet Grouping [Table Text Block]
Debt Disclosure [Abstract]
Debt [Text Block]
Debt Disclosure [Text Block]
Minimum Lease Payments [Abstract]
Minimum Lease Payments [Abstract]
Statement [Table]
Statement [Table]
Statement [Line Items]
Statement [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months
Operating Leases, Future Minimum Payments Due, Next Twelve Months
Operating Leases, Future Minimum Payments, Due in Two Years
Operating Leases, Future Minimum Payments, Due in Two Years
Operating Leases, Future Minimum Payments, Due in Three Years
Operating Leases, Future Minimum Payments, Due in Three Years
Operating Leases, Future Minimum Payments, Due in Four Years
Operating Leases, Future Minimum Payments, Due in Four Years
Operating Leases, Future Minimum Payments, Due in Five Years
Operating Leases, Future Minimum Payments, Due in Five Years
Operating Leases, Future Minimum Payments, Due Thereafter
Operating Leases, Future Minimum Payments, Due Thereafter
Schedule of Long-term Debt Instruments [Table]
Schedule of Long-term Debt Instruments [Table]
Long-term Debt, Type [Axis]
Long-term Debt, Type [Axis]
Long-term Debt, Type [Domain]
Long-term Debt, Type [Domain]
Revolving Credit Facility due 2019 [Member]
Line of Credit [Member]
6.80% Senior Notes due 2018 [Member]
Senior Notes Due 2018 [Member]
Senior Notes Due 2018.
6.80% Senior Notes Due 2020 [Member]
Senior Notes Due 2020 [Member]
Senior Notes Due 2020.
6.875% Senior Notes Due 2021 [Member]
Senior Notes Due 2021 [Member]
Senior Notes Due 2021.
5.375% Senior Notes Due 2022 [Member]
Senior Notes Due 2022 [Member]
Senior Notes Due 2022.
5.25% Senior Notes Due 2023 [Member]
5.25% Senior Notes Due 2023 [Member]
5.25% Senior Notes Due 2023 [Member]
5.625% Senior Notes Due 2026 [Member]
5.625% Senior Notes Due 2026 [Member]
5.625% Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Long-term Debt, Gross
Long-term Debt, Gross
Less unamortized discount
Debt Instrument, Unamortized Discount
Debt, Long-term and Short-term, Combined Amount
Debt, Long-term and Short-term, Combined Amount
Long-term debt
Long-term Debt
Total long-term debt outstanding
Long-term Debt, Excluding Current Maturities
Less: current portion of long-term debt
Long-term Debt, Current Maturities
Compensation and Employee Benefit Plans [Text Block]
Compensation and Employee Benefit Plans [Text Block]
Business Combinations [Abstract]
Acquisitions & Divestitures [Text Block]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]
Employee Benefits [Text Block]
Pension and Other Postretirement Benefits Disclosure [Text Block]
Asset Retirement Obligation [Abstract]
Asset Retirement Obligation Disclosure [Text Block]
Schedule of Asset Retirement Obligations [Table Text Block]
Schedule of Change in Asset Retirement Obligation [Table Text Block]
Schedule of Change in Asset Retirement Obligation [Table Text Block]
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Award Type [Axis]
Award Type [Axis]
Equity Award [Domain]
Equity Award [Domain]
Performance Share Units [Member]
Performance Share Units [Member]
Incremental common shares attributable to performance share units.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
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
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number
Shares granted
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
Shares vested
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period
Shares forfeited
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period
Unvested balance at end of period
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
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
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Weighted average grant date fair value, grants
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value
Weighted average grant date fair value, vested
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value
Weighted average grant date fair value, forfeited
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value
Weighted average grant date fair value, end of period
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table]
Antidilutive Securities [Axis]
Antidilutive Securities [Axis]
Antidilutive Securities, Name [Domain]
Antidilutive Securities, Name [Domain]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares
Anti-dilutive shares
Anti-dilutive shares
Weighted-average basic common shares outstanding
Weighted Average Number of Shares Outstanding, Basic
Potential number of shares issuable upon exercise of in-the-money stock options under the Long-Term Stock Incentive Plan
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements
Average diluted common shares outstanding
Weighted Average Number of Shares Outstanding, Diluted
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative [Table]
Derivative [Table]
Derivative Instrument [Axis]
Derivative Instrument [Axis]
Derivative Contract [Domain]
Derivative Contract [Domain]
Range [Axis]
Range [Axis]
Range [Domain]
Range [Domain]
Minimum [Member]
Minimum [Member]
Maximum [Member]
Maximum [Member]
Derivative [Line Items]
Derivative [Line Items]
Maximum Forecasted Production Covered By Derivatives
Maximum Forecasted Production Covered By Derivatives
Potential maximum amount of forecasted production covered by derivative contracts.
Expected Annual Production Covered By Derivatives
Expected Annual Production Covered By Derivatives
Expected Annual Production Covered By Derivatives
Commitments and Contingencies Disclosure [Abstract]
Commitment and Contingencies [Text Block]
Commitments and Contingencies Disclosure [Text Block]
Fair Value, by Balance Sheet Grouping [Table]
Fair Value, by Balance Sheet Grouping [Table]
Balance Sheet Location [Axis]
Balance Sheet Location [Axis]
Balance Sheet Location [Domain]
Balance Sheet Location [Domain]
Noncurrent Assets Held for Sale [Member]
Noncurrent Assets Held for Sale [Member]
Noncurrent Assets Held for Sale [Member]
Long-term [Member]
Long term [Member]
Derivative contracts with maturities in excess of one year.
Short-term [Member]
Short term [Member]
Derivative contracts with maturities of one year or less.
Fair Value, Measurements, Fair Value Hierarchy [Domain]
Level 1 [Member]
Fair Value, Inputs, Level 1 [Member]
Fair Value, Inputs, Level 2 [Member]
Fair Value, Inputs, Level 2 [Member]
Level 3 [Member]
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Assets
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross
Derivative Asset, Fair Value, Gross Asset
Derivative Asset, Netting Adjustments
Derivative Asset, Fair Value, Amount Offset Against Collateral
Derivative Asset, Net
Derivative Asset
Financial liabilities
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross
Derivative Liability, Fair Value, Gross Liability
Derivative Liability, Netting Adjustments
Derivative Liability, Fair Value, Amount Offset Against Collateral
Derivative Liability, Net
Derivative Liability
Haynesville Divestiture [Abstract]
Haynesville Divestiture [Abstract]
Schedule of Business Acquisitions, by Acquisition [Table]
Schedule of Business Acquisitions, by Acquisition [Table]
Accounts Receivable [Member]
Accounts Receivable [Member]
Scenario [Axis]
Scenario [Axis]
Scenario, Unspecified [Domain]
Scenario, Unspecified [Domain]
Total incurred to date [Member]
Total incurred to date [Member]
Total incurred to date [Member]
Asset Class [Axis]
Asset Class [Axis]
Asset Class [Domain]
Asset Class [Domain]
Property, Plant and Equipment [Member]
Property, Plant and Equipment [Member]
Other Noncurrent Assets [Member]
Other Noncurrent Assets [Member]
Other Current Liabilities [Member]
Other Current Liabilities [Member]
Asset Retirement Obligations, Current [Member]
Asset Retirement Obligations, Current [Member]
Asset Retirement Obligations, Current [Member]
Asset Retirement Obligations, Long Term [Member]
Asset Retirement Obligations, Long Term [Member]
Asset Retirement Obligations, Long Term [Member]
Derivative Financial Instruments, Liabilities [Member]
Derivative Financial Instruments, Liabilities [Member]
Other Noncurrent Liabilities [Member]
Other Noncurrent Liabilities [Member]
Other Current Assets [Member]
Other Current Assets [Member]
Business Divestiture [Axis]
Business Divestiture [Axis]
Business Divestiture [Axis]
Business Divestiture [Domain]
Business Divestiture [Domain]
[Domain] for Business Divestiture [Axis]
Haynesville Divestiture [Member]
Haynesville Divestiture [Member]
Haynesville Divestiture [Member]
Business Acquisition [Axis]
Business Acquisition [Axis]
Business Acquisition, Acquiree [Domain]
Business Acquisition, Acquiree [Domain]
Income Statement Location [Axis]
Income Statement Location [Axis]
Income Statement Location [Domain]
Income Statement Location [Domain]
Ownership [Axis]
Ownership [Axis]
Ownership [Domain]
Ownership [Domain]
Class of Stock [Axis]
Class of Stock [Axis]
Class of Stock [Domain]
Class of Stock [Domain]
Business Acquisition [Line Items]
Business Acquisition [Line Items]
Noncurrent assets held for sale
Disposal Group, Including Discontinued Operation, Assets, Noncurrent
Payments to acquire oil and gas property
Payments to Acquire Oil and Gas Property
Proceeds from Sale of Oil and Gas Property and Equipment
Proceeds from Sale of Oil and Gas Property and Equipment
Gain (Loss) on Disposition of Oil and Gas Property
Gain (Loss) on Disposition of Oil and Gas Property
Results of Operations, Loss before Income Taxes
Results of Operations, Loss before Income Taxes
Results of Operations, Loss before Income Taxes
Restructuring Charges
Restructuring Charges
Escrow Deposit
Escrow Deposit
Revenue Recognition [Abstract]
Revenue Recognition [Table]
Revenue Recognition [Table]
Adjustments for New Accounting Pronouncements [Axis]
Adjustments for New Accounting Pronouncements [Axis]
Type of Adoption [Domain]
Type of Adoption [Domain]
As reported [Member]
As reported [Member]
As reported [Member]
Revenues as Adjusted [Member]
Revenues as Adjusted [Member]
Revenues as adjusted [Member]
Adjustments for New Accounting Pronouncement [Member]
Adjustments for New Accounting Pronouncement [Member]
Income Statement, as adjusted [Member]
Income Statement, as adjusted [Member]
Income Statement, as adjusted [Member]
Revenue Recognition [Line Items]
Revenue Recognition [Line Items]
[Line Items] for Revenue Recognition [Table]
REVENUES
Revenues [Abstract]
Oil and condensate, gas and NGL sales
Exploration and Production Revenue
Other revenue
Gas Gathering, Transportation, Marketing and Processing Revenue
Purchased oil and gas sales
Revenue from Purchased Oil and Gas
Total Revenues
Oil and Gas Revenue
OPERATING EXPENSES
Operating Expenses [Abstract]
Purchased oil and gas expense
Cost of Purchased Oil and Gas
Lease operating expense
Oil and Gas Property, Lease Operating Expense
Transportation and processing costs
Gas Gathering, Transportation, Marketing and Processing Costs
Gathering and other expense
Other Cost and Expense, Operating
General and administrative
General and Administrative Expense
Production and property taxes
Production Tax Expense
Depreciation, depletion and amortization
Depreciation, Depletion and Amortization
Exploration expenses
Exploration Expense
Impairment
Asset Impairment Charges
Total Operating Expenses
Operating Expenses
Net gain (loss) from asset sales, inclusive of restructuring costs
OPERATING INCOME (LOSS)
Operating Income (Loss)
Realized and unrealized gains (losses) on derivative contracts (Note 7)
Gain (Loss) on Derivative Instruments, Net, Pretax
Interest and other income (expense)
Interest Income, Operating
Interest expense
Interest Expense
INCOME (LOSS) BEFORE INCOME TAXES
Results of Operations, Income before Income Taxes
Income tax (provision) benefit
Income Tax Expense (Benefit)
Net income (loss)
Net Income (Loss) Attributable to Parent
Earnings (loss) per common share
Basic
Earnings Per Share, Basic
Diluted
Earnings Per Share, Diluted
Weighted-average common shares outstanding
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Used in basic calculation
Used in diluted calculation
Dividends per common share
Common Stock, Dividends, Per Share, Cash Paid
Leases [Abstract]
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Line Items]
Lessee, Lease, Description [Line Items]
Lease, Cost [Table Text Block]
Lease, Cost [Table Text Block]
Lessee, Operating Leases [Text Block]
Lessee, Operating Leases [Text Block]
Statement of Stockholders' Equity [Abstract]
Equity Components [Axis]
Equity Components [Axis]
Equity Component [Domain]
Equity Component [Domain]
Common Stock, Value [Member]
Common Stock, Value [Member]
Common Stock, Value [Member]
Stockholders' Equity, Total
Stockholders' Equity, Total [Member]
Treasury Stock [Member]
Treasury Stock [Member]
Additional Paid-in Capital [Member]
Additional Paid-in Capital [Member]
Retained Earnings [Member]
Retained Earnings [Member]
Other Comprehensive Income (Loss) [Member]
Other Comprehensive Income (Loss) [Member]
Common Stock, Shares
Shares, Issued
Treasury Stock, Shares
Treasury Stock, Shares
Net income (loss), Shares
Stockholders' Equity, Other Shares
Net income (loss)
Common stock repurchased and retired, Shares
Stock Repurchased and Retired During Period, Shares
Common stock repurchased and retired
Stock Repurchased and Retired During Period, Value
Share-based compensation, Shares
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures
Share-based compensation
Stock Granted, Value, Share-based Compensation, Net of Forfeitures
Stock Issued During Period, Shares, Treasury Stock Reissued
Stock Issued During Period, Shares, Treasury Stock Reissued
Share-based compensation
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures
Stock Issued During Period, Shares, Employee Benefit Plan
Stock Issued During Period, Shares, Employee Benefit Plan
Change in pension and postretirement liability, net of tax
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax
Stockholders' Equity
Stockholders' Equity Attributable to Parent
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]
Restructuring Costs [Table Text Block]
Restructuring and Related Costs [Table Text Block]
Restructuring Costs, Liability [Table Text Block]
Restructuring Costs [Table Text Block]
[Table Text Block] for Restructuring Costs [Table]
Oil and Gas Production Type [Axis]
Oil and Gas Production Type [Axis]
Production Type [Domain]
Production Type [Domain]
Proved Property [Member]
Proved Property [Member]
Proved Property [Member]
Impairment of Oil and Gas Properties
Impairment of Oil and Gas Properties
Earnings Per Share [Text Block]
Earnings Per Share [Text Block]
subsequentevent [Abstract]
subsequentevent [Abstract]
Subsequent Event [Table]
Subsequent Event [Table]
Subsequent Event Type [Axis]
Subsequent Event Type [Axis]
Subsequent Event Type [Domain]
Subsequent Event Type [Domain]
Williston Basin Divestiture [Member]
Williston Basin Divestiture [Member]
Williston Basin Divestiture [Member]
Security Owned Not Readily Marketable [Axis]
Security Owned Not Readily Marketable [Axis]
Security Owned Not Readily Marketable [Domain]
Security Owned Not Readily Marketable, Name [Domain]
Threshold 1 [Member]
Threshold 1 [Member]
Threshold 1 [Member]
Threshold 2 [Member]
Threshold 2 [Member]
Threshold 2 [Member]
Subsequent Event [Line Items]
Subsequent Event [Line Items]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation [Text Block]
Nature of Operations [Text Block]
Share-based Compensation Expense [Table]
Share-based Compensation Expense [Table]
Share-based Compensation Expense [Table]
General and Administrative Expense [Member]
General and Administrative Expense [Member]
Stock Options [Member]
Employee Stock Option [Member]
Restricted Share Awards [Member]
Restricted Stock [Member]
Restricted Share Units (RSUs) [Member]
Restricted Stock Units (RSUs) [Member]
Restricted Shares [Member]
Restricted Shares [Member]
Restricted Shares [Member]
Restricted Share Units (RSUs) [Member]
Restricted Share Units (RSUs) [Member]
Restricted Share Units (RSUs) [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation Expense [Line Items]
[Line Items] for Share-based Compensation Expense [Table]
Allocated Share-based Compensation Expense
Allocated Share-based Compensation Expense
Accelerated Share Based Compensation
Accelerated Share Based Compensation
Accelerated Share Based Compensation
Share-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost
Schedule of Net Benefit Costs [Table Text Block]
Schedule of Net Benefit Costs [Table Text Block]
Uinta Basin Divestiture [Member]
Uinta Basin Divestiture [Member]
Uinta Basin Divestiture [Member]
Pinedale Divestiture [Member]
Pinedale Divestiture [Member]
Pinedale Divestiture [Member]
Derivative Instrument Contract Type [Axis]
Derivative Instrument Contract Type [Axis]
Information by name that identifies a derivative or a group of derivatives by (derivative) contract risk type.
Derivative Instrument Contract Type [Domain]
Derivative Instrument Contract Type [Domain]
The name that identifies a derivative or a group of derivatives, on a disaggregated basis, by contract risk type.
Oil derivative contracts [Member]
Oil derivative contracts [Member]
Derivative instrument whose primary underlying risk is tied to commodity prices.
Gas derivative contracts [Member]
Natural gas derivative contracts [Member]
Derivative instrument whose primary underlying risk is tied to commodity prices.
NGL derivative contracts [Member]
NGL derivative contracts [Member]
NGL derivative contract [Member]
Production [Member]
Production [Member]
Production [Member]
Storage [Member]
Storage [Member]
Storage [Member]
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments
Realized gain (loss) on commodity derivative contracts not designated as hedging instruments
Represents the realized gain (loss) on commodity derivative contracts not designated as hedging instruments for the period.
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments
Unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments
Represents the unrealized gain (loss) on commodity derivative contracts not designated as hedging instruments for the period.
Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments
Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments
Total Realized and Unrealized Gain (Loss) on Commodity Derivative Contracts Not Designated as Hedging Instruments
Components of basic and diluted shares used in EPS [Table Text Block]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Statement of Comprehensive Income [Abstract]
Postretirement medical plan changes, income tax expense
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax
Net curtailment (gain) loss, tax
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax
Pension and other postretirement plans adjustments:
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract]
Amortization of prior service cost, income tax expense
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax
Amortization of net actuarial loss, income tax expense
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax
Asset Retirement Obligation Disclosure [Abstract]
Divestitures [Table]
Divestitures [Table]
Divestitures [Table]
Divestitures [Line Items]
Divestitures [Line Items]
[Line Items] for Divestitures [Table]
ARO liability at January 1, 2019
Asset Retirement Obligation
Accretion
Asset Retirement Obligation, Accretion Expense
Additions
Asset Retirement Obligation, Liabilities Incurred
Revisions
Asset Retirement Obligation, Revision of Estimate
Liabilities related to assets sold(1)
ARO Liabilities Transferred
ARO Liabilities Transferred
Liabilities settled
Asset Retirement Obligation, Liabilities Settled
ARO Liability at March 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations [Table]
Disposal Groups, Including Discontinued Operations [Table]
Disposal Group Name [Axis]
Disposal Group Name [Axis]
Disposal Group Name [Domain]
Disposal Group Name [Domain]
Disposal Group Classification [Axis]
Disposal Group Classification [Axis]
Disposal Group Classification [Domain]
Disposal Group Classification [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncurrent Assets and Liabilities Held for Sale [Table Text Block]
Noncurrent Assets and Liabilities Held for Sale [Table Text Block]
[Table Text Block] for Noncurrent Assets and Liabilities Held for Sale [Table]
Disclosure of Long Lived Assets Held-for-sale [Table Text Block]
Disposal Groups, Including Discontinued Operations [Table Text Block]
Schedule of Operating Leased Assets [Table]
Schedule of Operating Leased Assets [Table]
Operating Leased Assets [Line Items]
Operating Leased Assets [Line Items]
Leases of Lessee Disclosure [Text Block]
Leases of Lessee Disclosure [Text Block]
Pinedale Divestiture [Abstract]
Pinedale Divestiture [Abstract]
Oil and Gas Delivery Commitments and Contracts [Axis]
Oil and Gas Delivery Commitments and Contracts [Axis]
Oil and Gas Delivery Commitments and Contracts
Oil and Gas Delivery Commitments and Contracts, Oil Producing Property [Domain]
Proceeds from disposition of assets
Income (loss) before income taxes
Minimum volume commitment
Long-term Purchase Commitment, Amount
Minimum volume commitment remaining
Purchase Commitment, Remaining Minimum Amount Committed
Schedule of Restructuring and Related Costs [Table]
Schedule of Restructuring and Related Costs [Table]
Segments [Axis]
Segments [Axis]
Segments [Domain]
Segments [Domain]
Year 2018 [Member]
Year 2018 [Member]
Year 2018 [Member]
Year 2019 [Member]
Year 2019 [Member]
Year 2019 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost
Restructuring and Related Cost, Expected Cost
Senior Notes Due 2023 [Member]
Senior Notes Due 2023 [Member]
Senior Notes Due 2023 [Member]
Senior Notes Due 2026 [Member]
Senior Notes Due 2026 [Member]
Senior Notes Due 2026
Long-term debt, interest rate (in hundredths)
Debt Instrument, Interest Rate, Stated Percentage
Maturity date of long-term debt
Debt Instrument, Maturity Date
Debt Maturity Period
Debt Maturity Period
Debt Maturity Period
Borrowing capacity
Line of Credit Facility, Current Borrowing Capacity
Long-term Debt, Weighted Average Interest Rate, at Point in Time
Long-term Debt, Weighted Average Interest Rate, at Point in Time
Letters of credit outstanding
Letters of Credit Outstanding, Amount
Principal amount of senior notes outstanding
Senior Notes
Debt Instrument, Maturity Date Range, Start
Debt Instrument, Maturity Date Range, Start
Debt Instrument, Maturity Date Range, End
Debt Instrument, Maturity Date Range, End
Senior Notes, stated interest rate, minimum (in hundredths)
Debt instrument, Stated Rate Range, Minimum
Debt instrument, Stated Rate Range, Minimum
Senior Notes, stated interest rate, maximim (in hundredths)
Debt Instrument, Stated Rate Range, Maximum
Debt Instrument, Stated Rate Range, Maximum
Other Acquisitions [Abstract]
Other Acquisitions [Abstract]
Permian Basin [Member]
Permian Basin [Member]
Permian Basin [Member]
2017 Permian Basin Acquisition [Member]
2017 Permian Basin Acquisition [Member]
2017 Permian Basin Acquisition [Member]
Permian Basin Acquisition [Member]
Permian Basin Acquisition [Member]
Permian Basin Acquisition [Member]
Other Acquisitions [Member]
Other Acquisitions [Member]
Other Acquisitions [Member]
Acquisition Costs, Period Cost
Acquisition Costs, Period Cost
Goodwill
Goodwill
Income Statement [Abstract]
Other revenues
Purchased oil and gas sales
OPERATING EXPENSES
Lease operating expense
General and administrative
Production and property taxes
Exploration expenses
OPERATING INCOME (LOSS)
Realized and unrealized gains (losses) on derivative contracts (Note 7)
Interest expense
INCOME (LOSS) BEFORE INCOME TAXES
Used in basic calculation
Fair Value, Inputs, Level 2 [Member]
Fair Value, Measurements, Recurring [Member]
Fair Value, Measurements, Recurring [Member]
Commodity Contract [Member]
Commodity Contract [Member]
Postretirement medical plan change(1)
Fair value of plan assets adjustment(1)
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)
Amortization of prior service costs
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax
Amortization of actuarial losses(2)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax
Curtailment Gain (Loss), after Tax(3)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax
Comprehensive income (loss)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Uinta Basin [Member]
Uinta Basin [Member]
Uinta Basin [Member]
Lessor, Lease, Description [Table]
Lessor, Lease, Description [Table]
Lease Operating Expense [Member]
Lease Operating Expense [Member]
Lease Operating Expense [Member]
Gathering and other expense [Member]
Gathering and other expense [Member]
Gathering and other expense [Member]
Lessor, Lease, Description [Line Items]
Lessor, Lease, Description [Line Items]
Lease, Cost
Lease, Cost
Operating Lease, Weighted Average Remaining Lease Term
Operating Lease, Weighted Average Remaining Lease Term
Operating Lease, Weighted Average Discount Rate, Percent
Operating Lease, Weighted Average Discount Rate, Percent
Share-based Compensation Expense [Table Text Block]
Share-based Compensation Expense [Table Text Block]
[Table Text Block] for Share-based Compensation Expense [Table]
Share-based Compensation, Stock Options, Activity [Table Text Block]
Share-based Compensation, Stock Options, Activity [Table Text Block]
Schedule of Share-based Compensation, Restricted Share Awards Activity [Table Text Block]
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]
Schedule of Other Share-based Compensation, PSUs & RSUs [Table Text Block]
Schedule of Other Share-based Compensation, Activity [Table Text Block]
Share-Based Compensation [Text Block]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]
Statement of Financial Position [Abstract]
Noncurrent [Axis]
Noncurrent [Axis]
Noncurrent [Axis]
Noncurrent [Domain]
Noncurrent [Domain]
[Domain] for Noncurrent [Axis]
Condensed Balance Sheet Statements, Captions [Line Items]
Condensed Balance Sheet Statements, Captions [Line Items]
ASSETS
Assets [Abstract]
Current Assets
Assets, Current [Abstract]
Cash and cash equivalents
Cash and Cash Equivalents, at Carrying Value
Accounts receivable, net
Accounts Receivable, Net, Current
Income tax receivable
Income Taxes Receivable, Current
Fair value of derivative contracts
Derivative Asset, Current
Prepaid expenses
Prepaid Expense, Current
Other current assets
Other Assets, Current
Total Current Assets
Assets, Current
Property, Plant and Equipment (successful efforts method for oil and gas properties)
Property, Plant and Equipment, Net [Abstract]
Proved properties
Proved Oil and Gas Property, Successful Effort Method
Unproved properties
Unproved Oil and Gas Property, Successful Effort Method
Gathering and other
Property, Plant and Equipment, Other, Gross
Materials and supplies
Inventory, Drilling, Noncurrent
Total Property, Plant and Equipment
Property, Plant and Equipment, Gross
Less Accumulated Depreciation, Depletion and Amortization
Depreciation, Depletion and Amortization, Nonproduction [Abstract]
Exploration and production
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization
Gathering and other
Property, Plant and Equipment, Other, Accumulated Depreciation
Total Accumulated Depreciation, Depletion and Amortization
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment
Net Property, Plant and Equipment
Property, Plant and Equipment, Net
Fair value of derivative contracts
Derivative Instruments and Hedges, Noncurrent
Operating Lease, Right-of-Use Asset
Operating Lease, Right-of-Use Asset
Other noncurrent assets
Other Assets, Noncurrent
TOTAL ASSETS
Assets
LIABILITIES AND EQUITY
Liabilities and Equity [Abstract]
Current Liabilities
Liabilities, Current [Abstract]
Checks outstanding in excess of cash balances
Bank Overdrafts
Accounts payable and accrued expenses
Accounts Payable and Accrued Liabilities, Current
Production and property taxes
Accrual for Taxes Other than Income Taxes, Current
Long-term Debt, Current Maturities
Interest payable
Interest Payable, Current
Fair value of derivative contracts
Derivative Liability, Current
Operating Lease, Liability, Current
Operating Lease, Liability, Current
Asset retirement obligations
Other Liabilities, Current
Total Current Liabilities
Liabilities, Current
Long-term debt
Deferred income taxes
Deferred Tax Liabilities, Net, Noncurrent
Asset retirement obligations
Asset Retirement Obligations, Noncurrent
Fair value of derivative contracts
Derivative Liability, Noncurrent
Operating Lease, Liability, Noncurrent
Operating Lease, Liability, Noncurrent
Other long-term liabilities
Other Liabilities, Noncurrent
Other long-term liabilities held for sale
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent
Commitments and contingencies (Note 11)
Commitments and Contingencies
EQUITY
Stockholders' Equity Attributable to Parent [Abstract]
Common stock – par value $0.01 per share; 500.0 million shares authorized; 242.0 million and 239.8 million shares issued, respectively
Common Stock, Value, Issued
Treasury stock – 3.9 million and 3.1 million shares, respectively
Treasury Stock, Value
Additional paid-in capital
Additional Paid in Capital, Common Stock
Retained earnings
Retained Earnings (Accumulated Deficit)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax
Total Common Shareholders' Equity
TOTAL LIABILITIES AND EQUITY
Liabilities and Equity
Debt Outstanding [Table Text Block]
Schedule of Debt [Table Text Block]
Operating Lease, Expense
Operating Lease, Expense
Operating Lease, Liability
Operating Lease, Liability
Statement of Cash Flows [Abstract]
OPERATING ACTIVITIES
Net Cash Provided by (Used in) Operating Activities [Abstract]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Deferred income taxes (benefit)
Deferred Income Tax Expense (Benefit)
Results of Operations, Dry Hole Costs
Results of Operations, Dry Hole Costs
Non-cash share-based compensation
Share-based Compensation
Amortization of debt issuance costs and discounts
Amortization of Debt Issuance Costs and Discounts
Bargain purchase gain from acquisition
Business Combination, Bargain Purchase, Gain Recognized, Amount
Net (gain) loss from asset sales, inclusive of restructuring costs
Unrealized (gains) losses on marketable securities
Marketable Securities, Unrealized Gain (Loss), Excluding Other than Temporary Impairments
Unrealized (gains) losses on derivative contracts
Unrealized Gain (Loss) on Derivatives
Other Operating Activities, Cash Flow Statement
Other Operating Activities, Cash Flow Statement
Changes in operating assets and liabilities
Increase (Decrease) in Operating Capital
Net Cash Provided by (Used in) Operating Activities
Net Cash Provided by (Used in) Operating Activities, Continuing Operations
INVESTING ACTIVITIES
Net Cash Provided by (Used in) Investing Activities [Abstract]
Property acquisitions
Property, plant and equipment, including exploratory well expense
Payments to Acquire Oil and Gas Equipment
Net Cash Provided by (Used in) Investing Activities
Net Cash Provided by (Used in) Investing Activities, Continuing Operations
FINANCING ACTIVITIES
Net Cash Provided by (Used in) Financing Activities [Abstract]
Checks outstanding in excess of cash balances
Increase (Decrease) in Outstanding Checks, Financing Activities
Long-term debt issuance costs paid
Payments of Debt Issuance Costs
Proceeds from credit facility
Proceeds from Long-term Lines of Credit
Repayments of credit facility
Repayments of Long-term Lines of Credit
Treasury stock repurchases
Payments for Repurchase of Common Stock
Other capital contributions
Proceeds from Contributed Capital
Net Cash Provided by (Used in) Financing Activities
Net Cash Provided by (Used in) Financing Activities, Continuing Operations
Change in cash, cash equivalents and restricted cash(1)
Cash and Cash Equivalents, Period Increase (Decrease)
Beginning cash, cash equivalents and restricted cash(1)
Restricted Cash and Cash Equivalents
Ending cash, cash equivalents and restricted cash(1)
Supplemental Disclosures:
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest, net of capitalized interest
Interest Paid, Net
Cash paid for income taxes, net
Income Taxes Paid, Net
Cash Paid for Amounts Included in the Measurement of Lease Liabilities
Cash Paid for Amounts Included in the Measurement of Lease Liabilities
Cash Paid for Amounts Included in the Measurement of Lease Liabilities
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability
Non-cash Investing Activities:
Noncash Investing and Financing Items [Abstract]
Change in capital expenditure accruals and other non-cash adjustments
Change in capital expenditure accruals and other non-cash adjustments
Change in capital expenditure accruals and other non-cash adjustments
Other Divestitures [Abstract]
Other Divestitures [Abstract]
Non-core properties Divestitures [Member]
Non-core properties Divestitures [Member]
Non-core properties Divestitures [Member]
Other Expense [Member]
Other Expense [Member]
Termination Benefits [Member]
Termination Benefits [Member]
Termination Benefits [Member]
Office lease Termination Costs [Member]
Lease Termination Costs [Member]
Lease Termination Costs [Member]
Accelerated Share Based Compensation [Member]
Accelerated Share Based Compensation [Member]
Accelerated Share Based Compensation [Member]
Retention Expense [Member]
Retention Expense [Member]
Retention Expense [Member]
Pension curtailment [Member]
Pension curtailment [Member]
Pension curtailment [Member]
Termination benefits
Termination Benefits
Termination Benefits
Office lease termination costs
Loss on Contract Termination
Accelerated share-based compensation(1)
Retention expense (including share-based compensation)
Retention expense
Retention expense
Total restructuring costs
Restructuring Costs
Costs recognized period from inception to March 31, 2019(1)
Restructuring and Related Cost, Cost Incurred to Date
Total remaining costs expected to be incurred
Restructuring Costs, Expected Costs
Restructuring Costs, Expected Costs
Cash and Cash Equivalents [Abstract]
Restrictions on Cash and Cash Equivalents [Table]
Restrictions on Cash and Cash Equivalents [Table]
Restricted Cash and Cash Equivalents [Axis]
Restricted Cash and Cash Equivalents [Axis]
Cash and Cash Equivalents [Domain]
Cash and Cash Equivalents [Domain]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash(1)
Restricted Cash and Investments
Total cash, cash equivalents and restricted cash shown in the Condensed Consolidated Statements of Cash Flows
Asset retirement obligations, current liability
Asset Retirement Obligation, Current
Other long-term liabilities held for sale
Liabilities, Noncurrent
Total ARO Liability
Consolidation Items [Axis]
Consolidation Items [Axis]
Consolidation Items [Domain]
Consolidation Items [Domain]
Restructuring Plan [Axis]
Restructuring Plan [Axis]
Restructuring Plan [Domain]
Restructuring Plan [Domain]
Other Comprehensive Income Location [Axis]
Other Comprehensive Income Location [Axis]
Other Comprehensive Income Location [Domain]
Other Comprehensive Income Location [Domain]
Restructuring Liability
Restructuring Reserve
Costs incurred and charged to expense
Restructuring and Related Cost, Incurred Cost
Costs paid or otherwise settled
Restructuring Costs, Paid or Settled
Restructuring Costs, Paid or Settled
Employee Retention Bonus Cost
Employee Retention Bonus Cost
Employee Retention Bonus Cost
Pension Plan and SERP [Member]
Pension Plan and SERP [Member]
Pension Plan and SERP [Member]
Service cost
Defined Benefit Plan, Service Cost
Interest cost
Defined Benefit Plan, Interest Cost
Expected return on plan assets
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Amortization of prior service costs(1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment
Amortization of actuarial losses(1)
Defined Benefit Plan, Amortization of Gain (Loss)
Curtailment (gain) loss(2)
Periodic expense
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Revenue Recognition [Text Block]
Revenue Recognition [Text Block]
Revenue Recognition [Text Block]
Common stock, par value (in dollars per share)
Common Stock, Par or Stated Value Per Share
Common stock, shares authorized (in shares)
Common Stock, Shares Authorized
Common stock, shares issued (in shares)
Common Stock, Shares, Issued
Treasury stock (in shares)
Schedule of Restricted Share Unit Transactions [Abstract]
Schedule of Restricted Share Unit Transactions [Abstract]
Operating Activities [Axis]
Operating Activities [Axis]
Operating Activities [Domain]
Operating Activities [Domain]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
Stock option exercises, intrinsic value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value
Shares available for future grants
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
Unrecognized compensation costs
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized
Weighted average vesting period
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
Award vesting period
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period
Total fair value of stock that vested during the period
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value
Disaggregated Revenue [Abstract]
Disaggregated Revenue [Abstract]
Geographical [Axis]
Geographical [Axis]
Geographical [Domain]
Geographical [Domain]
Williston Basin [Member]
Williston Basin [Member]
Williston Basin [Member]
Pinedale [Member]
Pinedale [Member]
Pinedale [Member]
Other Northern [Member]
Other Northern [Member]
Other Northern [Member]
Haynesville/Cotton Valley [Member]
Haynesville [Member]
Haynesville [Member]
Other Southern [Member]
Other Southern [Member]
Other Southern [Member]
Oil and condensate sales
Oil and Condensate Revenue
Gas sales
Natural Gas Production Revenue
NGL sales
Natural Gas Midstream Revenue
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]
Asset Retirement Obligations [Text Block]
Asset Retirement Obligation Disclosure [Text Block]
Measurement Basis [Axis]
Measurement Basis [Axis]
Fair Value Measurement [Domain]
Fair Value Measurement [Domain]
Portion at Fair Value Measurement [Member]
Portion at Fair Value Measurement [Member]
Reported Value Measurement [Member]
Reported Value Measurement [Member]
Estimate of Fair Value Measurement [Member]
Estimate of Fair Value Measurement [Member]
Cash and Cash Equivalents, at Carrying Value
Long-term debt, fair value
Long-term Debt, Fair Value
Document And Entity Information [Abstract]
Document and Entity Information [Abstract]
Entity Registrant Name
Entity Registrant Name
Entity Central Index Key
Entity Central Index Key
Current Fiscal Year End Date
Current Fiscal Year End Date
Entity Well-known Seasoned Issuer
Entity Well-known Seasoned Issuer
Entity Voluntary Filers
Entity Voluntary Filers
Entity Current Reporting Status
Entity Current Reporting Status
Entity Filer Category
Entity Filer Category
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Document Fiscal Year Focus
Document Fiscal Year Focus
Document Fiscal Period Focus
Document Fiscal Period Focus
Document Type
Document Type
Amendment Flag
Amendment Flag
Document Period End Date
Document Period End Date
Subsequent Events [Abstract]
Subsequent Events [Text Block]
Subsequent Events [Text Block]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]
Derivative Instruments, Gain (Loss) [Table Text Block]
Derivative Instruments, Gain (Loss) [Table Text Block]
Restructuring [Abstract]
Restructuring [Abstract]
Restructuring and Related Activities Disclosure [Text Block]
Restructuring and Related Activities Disclosure [Text Block]
Oil Swaps [Member]
Oil Swaps [Member]
Oil Swaps [Member]
Gas Swaps [Member]
Gas Swaps [Member]
Gas Swaps [Member]
Oil Basis Swaps [Member]
Oil Basis Swaps [Member]
Oil Basis Swaps [Member]
Gas Basis Swaps [Member]
Gas Basis Swaps [Member]
Gas Basis Swaps [Member]
Derivative Contract Year [Axis]
Derivative Contract Year [Axis]
Tabular presentation of derivative instruments by year of contract.
Derivative Contract Year [Domain]
Derivative Contract Year [Domain]
Tabular presentation of derivative instruments by year of contract.
Year 2020 [Member]
Year 2020 [Member]
Year 2020 [Member]
Energy Commodities Exchange [Axis]
Energy Commodities Exchange [Axis]
Exchange where various commodities and derivatives products are traded
Energy Commodities Exchange Abbreviation [Domain]
Energy Commodities Exchange Abbreviation [Domain]
Exchange abbreviation where various commodities and derivatives products are traded.
NYMEX WTI [Member]
NYMEX WTI [Member]
Energy Commodities Exchange Abbreviation
ICE Brent [Member]
ICE Brent [Member]
ICE Brent [Member]
NYMEX HH [Member]
NYMEX HH [Member]
NYMEX HH [Member]
NYMEX WTI less Argus WTI Midland [Member]
NYMEX WTI less Argus WTI Midland [Member]
NYMEX WTI less Argus WTI Midland [Member]
NYMEX WTI less Argus WTI Houston [Member]
NYMEX WTI less Argus WTI Houston [Member]
NYMEX WTI less Argus WTI Houston [Member]
NYMEX HH LESS IFNPCR [Member]
NYMEX HH LESS IFNPCR [Member]
NYMEX HH LESS IFNPCR [Member]
Derivative Volumes
Derivative, Nonmonetary Notional Amount
Average Swap Price per Unit
Average Swap Price per Unit
Average Swap Price per Unit
Weighted-Average Differential
Underlying, Derivative
Restricted Cash [Abstract]
Restrictions on Cash and Cash Equivalents [Table Text Block]
Restrictions on Cash and Cash Equivalents [Table Text Block]
Impairment of Long Lived Assets [Abstract]
Impairment of Long Lived Assets [Abstract]
Schedule of Impaired Long-Lived Assets Held and Used [Table]
Schedule of Impaired Long-Lived Assets Held and Used [Table]
Impaired Long-Lived Assets Held and Used by Type [Axis]
Impaired Long-Lived Assets Held and Used by Type [Axis]
Impaired Long-Lived Assets Held and Used, Asset Name [Domain]
Impaired Long-Lived Assets Held and Used, Asset Name [Domain]
Other impairment [Member]
Other impairment [Member]
Other impairment [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impaired Long-Lived Assets Held and Used [Line Items]
Revenue Recognition 606 [Table Text Block]
Revenue Recognition 606 [Table Text Block]
Revenue Recognition 606 [Table Text Block]
Revenue Recognition [Table Text Block]
Revenue Recognition [Table Text Block]
[Table Text Block] for Revenue Recognition [Table]
Plan Name [Axis]
Plan Name [Axis]
Plan Name [Domain]
Plan Name [Domain]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number
Options granted
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross
Options exercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Options forfeited
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares
Options canceled
Share-based Compensation Arrangement by Share-based Payment Award, Options, Other Increases (Decreases) in Period
Outstanding at end of period
Options exercisable, shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number
Unvested options, shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average exercise price, beginning of year
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price
Weighted average exercise price, granted in period
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price
Weighted average exercise price, exercised in period
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price
Weighted average exercise price, forfeited in period
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price
Weighted average exercise price, canceled in period
Share-based Compensation Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price
Weighted average exercise price, end of year
Options exercisable, weighted average exercise price
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price
Unvested options, weighted average exercise price
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value
Weighted average remaining contractual term, options outstanding
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term
Weighted average remaining contractual term, options exercisable
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term
Weighted average remaining contractual term, options unvested
Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Weighted Average Remaining Contractual Term
The weighted average period between the balance sheet date and expiration for all unvested portions of options outstanding under the plan, which may be expressed in a decimal value for number of years.
Aggregate intrinsic value, options outstanding
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value
Aggregate intrinsic value, options exercisable
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Aggregate intrinsic value, options unvested
Sharebased Compensation Arrangement By Sharebased Payment Award Options Unvested Intrinsic Value1
The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of unvested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.