Condensed Consolidating Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	$ 853	$ 951	[1]
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(1,070)	(928)	[1]
Business combination, net	(353)	0	[1]
Acquisitions of proved and unproved properties	(17)	(102)	[1]
Proceeds from divestitures of proved and unproved properties	82	384	[1]
Additions to other property and equipment	(18)	(5)	[1]
Other investing activities	4	148
Net Cash Used In Investing Activities	(1,372)	(503)	[1]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	6,416	6,118	[1]
Payments on revolving credit facility borrowings	(5,452)	(6,393)	[1]
Cash paid to purchase debt	(381)	0	[1]
Cash paid for preferred stock dividends	(46)	(46)	[1]
Other financing activities	(18)	(129)
Intercompany advances, net	0	0
Net Cash Provided By (Used In) Financing Activities	519	(450)	[1]
Net decrease in cash and cash equivalents	0	(2)	[1]
Cash and cash equivalents, beginning of period	4	5	[1]
Cash and cash equivalents, end of period	4	3	[1]
Eliminations
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	(2)	(8)
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
Cash paid to purchase debt	0
Cash paid for preferred stock dividends	0	0
Other financing activities	2	6
Intercompany advances, net	0	0
Net Cash Provided By (Used In) Financing Activities	2	6
Net decrease in cash and cash equivalents	0	(2)
Cash and cash equivalents, beginning of period	(2)	(3)
Cash and cash equivalents, end of period	(2)	(5)
Parent | Reportable legal entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	0	88
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	6,119	6,118
Payments on revolving credit facility borrowings	(5,166)	(6,393)
Cash paid to purchase debt	(381)
Cash paid for preferred stock dividends	(46)	(46)
Other financing activities	(12)	(2)
Intercompany advances, net	(515)	235
Net Cash Provided By (Used In) Financing Activities	(1)	(88)
Net decrease in cash and cash equivalents	(1)	0
Cash and cash equivalents, beginning of period	4	5
Cash and cash equivalents, end of period	3	5
Guarantor Subsidiaries | Reportable legal entities
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	613	866
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(805)	(928)
Business combination, net	(381)
Acquisitions of proved and unproved properties	(17)	(102)
Proceeds from divestitures of proved and unproved properties	82	384
Additions to other property and equipment	(7)	(5)
Other investing activities	4	148
Net Cash Used In Investing Activities	(1,124)	(503)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	0	0
Payments on revolving credit facility borrowings	0	0
Cash paid to purchase debt	0
Cash paid for preferred stock dividends	0	0
Other financing activities	(4)	(126)
Intercompany advances, net	515	(237)
Net Cash Provided By (Used In) Financing Activities	511	(363)
Net 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	242	5
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(265)	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	(11)	0
Other investing activities	0	0
Net Cash Used In Investing Activities	(248)	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility borrowings	297	0
Payments on revolving credit facility borrowings	(286)	0
Cash paid to purchase debt	0
Cash paid for preferred stock dividends	0	0
Other financing activities	(4)	(7)
Intercompany advances, net	0	2
Net Cash Provided By (Used In) Financing Activities	7	(5)
Net decrease in cash and cash equivalents	1	0
Cash and cash equivalents, beginning of period	1	2
Cash and cash equivalents, end of period	$ 2	$ 2

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