Condensed Combined Debtor-in-Possession Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	$ 1,155	$ 1,182
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(946)	(1,640)
Business combination, net	0	(353)
Acquisitions of proved and unproved properties	(9)	(31)
Proceeds from divestitures of proved and unproved properties	10	110
Additions to other property and equipment	(18)	(27)
Proceeds from sales of other property and equipment	5	6
Net Cash Used In Investing Activities	(958)	(1,935)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from pre-petition revolving credit facility borrowings	3,806	8,805
Payments on pre-petition revolving credit facility borrowings	(3,467)	(7,495)
Proceeds from DIP credit facility borrowings	60	0
DIP credit facility and exit facilities financing costs	(109)	0
Cash paid to purchase debt	(95)	(457)
Cash paid for preferred stock dividends	(22)	(69)
Other financing activities	(10)	(21)
Net Cash Provided By Financing Activities	103	763
Net increase in cash and cash equivalents	300	10
Cash and cash equivalents, beginning of period	6	4
Cash and cash equivalents, end of period	306	14
Debtor-in-Possession
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Cash Provided By Operating Activities	1,153	1,178
CASH FLOWS FROM INVESTING ACTIVITIES:
Drilling and completion costs	(946)	(1,640)
Business combination, net	0	(353)
Acquisitions of proved and unproved properties	(9)	(31)
Proceeds from divestitures of proved and unproved properties	10	110
Additions to other property and equipment	(18)	(27)
Proceeds from sales of other property and equipment	5	6
Net Cash Used In Investing Activities	(958)	(1,935)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from pre-petition revolving credit facility borrowings	3,806	8,805
Payments on pre-petition revolving credit facility borrowings	(3,467)	(7,495)
Proceeds from DIP credit facility borrowings	60	0
Payments on DIP credit facility borrowings	(60)	0
DIP credit facility and exit facilities financing costs	(109)	0
Cash paid to purchase debt	(95)	(457)
Cash paid for preferred stock dividends	(22)	(69)
Other financing activities	(8)	(19)
Net Cash Provided By Financing Activities	105	765
Net increase in cash and cash equivalents	300	8
Cash and cash equivalents, beginning of period	4	3
Cash and cash equivalents, end of period	$ 304	$ 11