Derivative and Hedging Activities - Cash Flow Hedges Components of AOCI (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended
	Feb. 09, 2021	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, after tax, beginning of period	$ 45
Losses reclassified to income, after tax	3	$ 0	$ 9
Cash flow hedging
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, before tax, beginning of period	(12)	0	(45)
AOCI, after tax, beginning of period	45	0	12
Losses reclassified to income, before tax	3	0	9
Losses reclassified to income, after tax	3	0	9
Fresh start adjustments, before tax	9	0	0
Fresh start adjustments, after tax	9	0	0
Elimination of tax effects, before tax	0	0	0
Elimination of tax effects, after tax	(57)	0	0
AOCI, before tax, end of period	0	0	(36)
AOCI, after tax, end of period	$ 0	$ 0	$ 21