Fresh Start Accounting - Cumulative Net Impact on Accumulated Deficit (Details) - USD ($) $ in Millions		1 Months Ended	2 Months Ended	3 Months Ended
	Feb. 09, 2021	Feb. 09, 2021	Mar. 31, 2021	Mar. 31, 2020
Reorganizations [Abstract]
Gain on settlement of liabilities subject to compromise	$ 6,443
Accrual of professional service provider success fees	(38)	$ (38)
Accrual of professional service provider fees	(5)	(5)
Surrender of other receivable	(18)	(18)
Payment of FLLO alternative transaction fee	(12)
Total reorganization items, net	6,370	(5,569)	$ 0	$ 0
Cancellation of predecessor equity	18,571	18,571
Accumulated deficit	$ 24,941	$ 24,941