CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Statement of Cash Flows (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended
	Feb. 28, 2017	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
CASH FLOW FROM OPERATING ACTIVITIES
Net (loss) income		$ (47)	$ (140)		$ 5	$ (190)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		138	138		278	285
Deferred income tax benefit				$ (78)		(78)
Net derivative (gains) losses		(43)	118		(116)	143
Net proceeds on settled derivatives					7	75
Net gains on early extinguishment of debt			(44)		(4)	(133)
Deferred gain and issuance costs amortization					(26)	(29)
Gains on asset divestitures	$ (21)		(31)		(21)	(31)
Other non-cash losses in income, net					17	43
Dry hole expenses					1
Changes in operating assets and liabilities, net					(21)	(41)
Net cash provided by operating activities					120	44
CASH FLOW FROM INVESTING ACTIVITIES
Capital investments					(132)	(26)
Changes in capital investment accruals					26	(11)
Asset divestitures					33	19
Acquisitions and other					(1)
Net cash used by investing activities					(74)	(18)
CASH FLOW FROM FINANCING ACTIVITIES
Proceeds from revolving credit facility					728	743
Repayments of revolving credit facility					(733)	(701)
Payments on first-lien first-out term loan					(66)	(61)
Debt repurchases					(24)	(13)
Debt transaction costs					(2)	(7)
Contribution from noncontrolling interest, net					49
Dividends paid to noncontrolling interest					(1)
Employee stock purchases and other						3
Net cash provided (used) by financing activities					(49)	(36)
(Decrease) increase in cash and cash equivalents					(3)	(10)
Cash and cash equivalents-beginning of period				12	12	12
Cash and cash equivalents-end of period		9	2		9	2
Parent | Reportable Legal Entity
CASH FLOW FROM OPERATING ACTIVITIES
Net (loss) income		(124)	(81)		(259)	(44)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		2	1		3	3
Deferred income tax benefit						(78)
Net gains on early extinguishment of debt			(44)		(4)	(133)
Deferred gain and issuance costs amortization					(26)	(29)
Other non-cash losses in income, net					10	23
Changes in operating assets and liabilities, net					(43)	(50)
Net cash provided by operating activities					(319)	(308)
CASH FLOW FROM INVESTING ACTIVITIES
Capital investments					(1)	(1)
Net cash used by investing activities					(1)	(1)
CASH FLOW FROM FINANCING ACTIVITIES
Proceeds from revolving credit facility					728	743
Repayments of revolving credit facility					(733)	(701)
Payments on first-lien first-out term loan					(66)	(61)
Debt repurchases					(24)	(13)
Debt transaction costs					(2)	(7)
Intercompany					418	347
Employee stock purchases and other						3
Net cash provided (used) by financing activities					321	311
(Decrease) increase in cash and cash equivalents					1	2
Cash and cash equivalents-end of period		1	2		1	2
Combined Guarantor Subsidiaries | Reportable Legal Entity
CASH FLOW FROM OPERATING ACTIVITIES
Net (loss) income		76	(59)		264	(146)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		133	137		272	282
Net derivative (gains) losses		(43)	118		(117)	143
Net proceeds on settled derivatives					7	75
Gains on asset divestitures			$ (31)		(21)	(31)
Other non-cash losses in income, net					7	20
Dry hole expenses					1
Changes in operating assets and liabilities, net					24	9
Net cash provided by operating activities					437	352
CASH FLOW FROM INVESTING ACTIVITIES
Capital investments					(131)	(25)
Changes in capital investment accruals					26	(11)
Asset divestitures					33	19
Acquisitions and other					46
Net cash used by investing activities					(26)	(17)
CASH FLOW FROM FINANCING ACTIVITIES
Intercompany					(417)	(347)
Net cash provided (used) by financing activities					(417)	(347)
(Decrease) increase in cash and cash equivalents					(6)	(12)
Cash and cash equivalents-beginning of period				$ 12	12	$ 12
Cash and cash equivalents-end of period		6			6
Combined Non-Guarantor Subsidiaries | Reportable Legal Entity
CASH FLOW FROM OPERATING ACTIVITIES
Net (loss) income		1
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		3			3
Net derivative (gains) losses					1
Changes in operating assets and liabilities, net					(2)
Net cash provided by operating activities					2
CASH FLOW FROM INVESTING ACTIVITIES
Acquisitions and other					(47)
Net cash used by investing activities					(47)
CASH FLOW FROM FINANCING ACTIVITIES
Contribution from noncontrolling interest, net					49
Dividends paid to noncontrolling interest					(1)
Intercompany					(1)
Net cash provided (used) by financing activities					47
(Decrease) increase in cash and cash equivalents					2
Cash and cash equivalents-end of period		$ 2			$ 2