Chapter 11 Proceedings and Ability to continue as a Going Concern - Schedule of Debtor in Possession Consolidated Financial Statements (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 13, 2019	Dec. 31, 2021	Dec. 31, 2020
Revenues [Abstract]
Revenues	$ 261	$ 4,954	$ 3,645	$ 3,685
Operating Expenses	(260)	(6,136)	(3,529)	(5,171)
Operating Loss	1	(1,182)	116	(1,486)
Other Expense:
Reorganization Items	(4)	5,389	0	(9)
Interest Expense, Net	(12)	(362)	(260)	(251)
Income (Loss) Before Income Taxes	(15)	3,819	(343)	(1,814)
Income Tax Provision	(9)	(135)	(86)	(85)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total	(24)	3,684	(429)	(1,899)
Cash Flows from Operating Activities:
Net Income (Loss)	(24)	3,684	(429)	(1,899)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Reorganization Items	0	136		0
Other Assets and Liabilities, Net	76	(11)	54	79
Net Cash Provided by (Used in) Operating Activities	61	(747)	322	210
Cash Flows From Financing Activities:
Borrowings from Debtor in Possession Credit Facility, net	0	1,529	0	0
Debtor in Possession Financing Payments and Payments on Backstop Agreement	0	(137)	0	0
Borrowings (Repayments) of Short-term Debt, Net	(1)	(347)	(4)	(27)
Other Financing Activities Among Subsidiaries	0	(49)	(28)	(45)
Net Cash Provided by (Used in) Financing Activities, Total	(2)	749	(403)	348
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	754	602	1,285	800
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 800	$ 754	$ 1,113	$ 1,285