Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 8,167	$ 8,367	[1]
Total other comprehensive (loss) income, net of tax	87	(18)
Ending balance	8,153	8,390	[1]
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(640)	(599)	[1]
Other comprehensive income (loss) before reclassification, net of tax	93	(2)
Amounts reclassified from AOCI, net of tax	(6)	(16)
Total other comprehensive (loss) income, net of tax	87	(18)
Ending balance	(553)	(617)	[1]
Debt Securities AFS
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(653)	(581)
Other comprehensive income (loss) before reclassification, net of tax	93	(70)
Amounts reclassified from AOCI, net of tax	0	0
Total other comprehensive (loss) income, net of tax	93	(70)
Ending balance	(560)	(651)
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	47	10
Other comprehensive income (loss) before reclassification, net of tax	0	68
Amounts reclassified from AOCI, net of tax	(7)	(17)
Total other comprehensive (loss) income, net of tax	(7)	51
Ending balance	40	61
Pension and Post-retirement Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(34)	(28)
Other comprehensive income (loss) before reclassification, net of tax	0	0
Amounts reclassified from AOCI, net of tax	1	1
Total other comprehensive (loss) income, net of tax	1	1
Ending balance	$ (33)	$ (27)

[1] On June 27, 2024, the Company announced a 1 for 3 reverse stock split, effective July 11, 2024. This reverse stock split is reflected retroactively in all periods presented. See Note 1 - Organization and Basis of Presentation.