Condensed Consolidating Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	$ 1,182	$ 1,395	[1]
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(1,640)	(1,407)	[1]
Business combination, net	(353)	0	[1]
Acquisitions of proved and unproved properties	(31)	(118)	[1]
Proceeds from divestitures of proved and unproved properties	110	395	[1]
Additions to other property and equipment	(27)	(11)	[1]
Other investing activities	6	149
Net Cash Used In Investing Activities	(1,935)	(992)	[1]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	8,805	9,095	[1]
Payments on revolving credit facility borrowings	(7,495)	(9,231)	[1]
Proceeds from issuance of senior notes, net	0	1,237	[1]
Cash paid to purchase debt	(457)	(1,285)	[1]
Cash paid for preferred stock dividends	(69)	(69)	[1]
Other financing activities	(21)	(151)
Intercompany advances, net	0	0
Net Cash Provided By (Used In) Financing Activities	763	(404)	[1]
Net increase (decrease) in cash and cash equivalents	10	(1)	[1]
Cash and cash equivalents, beginning of period	4	5	[1]
Cash and cash equivalents, end of period	14	4	[1]
Eliminations
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	(3)	(10)
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	0	0
Business combination, net	0
Acquisitions of proved and unproved properties	0	0
Proceeds from divestitures of proved and unproved properties	0	0
Additions to other property and equipment	0	0
Other investing activities	0	0
Net Cash Used In Investing Activities	0	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	0	0
Payments on revolving credit facility borrowings	0	0
Proceeds from issuance of senior notes, net		0
Cash paid to purchase debt	0	0
Cash paid for preferred stock dividends	0	0
Other financing activities	3	(13)
Intercompany advances, net	(1)	22
Net Cash Provided By (Used In) Financing Activities	2	9
Net increase (decrease) in cash and cash equivalents	(1)	(1)
Cash and cash equivalents, beginning of period	(2)	(3)
Cash and cash equivalents, end of period	(3)	(4)
Parent | Reportable legal entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	0	86
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	0	0
Business combination, net	0
Acquisitions of proved and unproved properties	0	0
Proceeds from divestitures of proved and unproved properties	0	0
Additions to other property and equipment	0	0
Other investing activities	0	0
Net Cash Used In Investing Activities	0	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	8,096	9,095
Payments on revolving credit facility borrowings	(7,011)	(9,231)
Proceeds from issuance of senior notes, net		1,237
Cash paid to purchase debt	(381)	(1,285)
Cash paid for preferred stock dividends	(69)	(69)
Other financing activities	(13)	(2)
Intercompany advances, net	(620)	170
Net Cash Provided By (Used In) Financing Activities	2	(85)
Net increase (decrease) in cash and cash equivalents	2	1
Cash and cash equivalents, beginning of period	4	5
Cash and cash equivalents, end of period	6	6
Guarantor Subsidiaries | Reportable legal entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	898	1,312
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(1,204)	(1,407)
Business combination, net	(381)
Acquisitions of proved and unproved properties	(31)	(118)
Proceeds from divestitures of proved and unproved properties	110	395
Additions to other property and equipment	(12)	(11)
Other investing activities	6	149
Net Cash Used In Investing Activities	(1,512)	(992)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	0	0
Payments on revolving credit facility borrowings	0	0
Proceeds from issuance of senior notes, net		0
Cash paid to purchase debt	0	0
Cash paid for preferred stock dividends	0	0
Other financing activities	(6)	(127)
Intercompany advances, net	620	(193)
Net Cash Provided By (Used In) Financing Activities	614	(320)
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	1	1
Cash and cash equivalents, end of period	1	1
Non-Guarantor Subsidiaries | Reportable legal entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	287	7
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(436)	0
Business combination, net	28
Acquisitions of proved and unproved properties	0	0
Proceeds from divestitures of proved and unproved properties	0	0
Additions to other property and equipment	(15)	0
Other investing activities	0	0
Net Cash Used In Investing Activities	(423)	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	709	0
Payments on revolving credit facility borrowings	(484)	0
Proceeds from issuance of senior notes, net		0
Cash paid to purchase debt	(76)	0
Cash paid for preferred stock dividends	0	0
Other financing activities	(5)	(9)
Intercompany advances, net	1	1
Net Cash Provided By (Used In) Financing Activities	145	(8)
Net increase (decrease) in cash and cash equivalents	9	(1)
Cash and cash equivalents, beginning of period	1	2
Cash and cash equivalents, end of period	$ 10	$ 1

[1] Financial information for 2018 has been recast to reflect the retrospective application of the successful efforts method of accounting. See Note 1.