Income Taxes (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended
	Feb. 09, 2021	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Effective income tax rate	1.10%	0.00%		0.20%
Income tax benefit	$ 57	$ 0	$ 57	$ 13
Deferred tax asset, operating loss carryforward, limitations		54	54
Cancellation of debt income			5,000
Federal
Business Acquisition [Line Items]
NOL carryforwards, subject to expiration		900	900
Federal | Minimum
Business Acquisition [Line Items]
NOL carryforwards					$ 2,500
NOL carryforwards, not subject to expiration		1,600	1,600
Federal | Maximum
Business Acquisition [Line Items]
NOL carryforwards					$ 3,000
NOL carryforwards, not subject to expiration		$ 2,100	$ 2,100