Chapter 11 Proceedings and Ability to continue as a Going Concern - Reorganziation Items (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
Reorganizations [Abstract]
Debtor Reorganization Items, Discharge of Claims and Liabilities	$ 0	$ 4,297		$ 0
Debtor Reorganization Items, Revaluation of Assets and Liabilities	0	1,434		0
Debtor Reorganization Items subtotal for Gain on Settlement of LSTC and Fair Value Adjustment	0	5,731		0
Unamortized Debt Issuance and Discount Expensed	0	(128)		0
Unamortized Interest Rate Derivative Loss Expensed	0	(8)		0
Reorganization Items	0	(136)		0
Backstop Commitment Fees	0	(81)		0
DIP Financing Fees	0	(56)		0
Professional Fees	(4)	(69)		(9)
Reorganization Items (Fees)	(4)	(206)		(9)
Total Reorganization Items	(4)	5,389	$ 0	(9)
Reorganization Items (Fees) Unpaid	30	30		0
Reorganization Items (Fees) Paid	$ 4	$ 176		$ 39