Components of Other Comprehensive Income (Loss) - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 8,551	$ 8,697	$ 8,494	$ 8,565	$ 8,307	$ 8,307	$ 8,494	$ 8,307
Net unrealized gains (losses)	(471)			(39)			(1,152)	(103)
Amounts reclassified from AOCI	7			1			13	2
Other comprehensive income (loss)	(464)	(252)	(423)	(38)	38	(101)	(1,139)	(101)
Balance, end of period	8,283	8,551	8,697	8,532	8,565	8,307	8,283	8,532
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(963)		(288)	(203)		(140)	(288)	(140)
Balance, end of period	(1,427)	(963)		(241)	(203)		(1,427)	(241)
Securities AFS
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(671)		(36)	43		108	(36)	108
Net unrealized gains (losses)	(368)			(38)			(1,003)	(103)
Amounts reclassified from AOCI	0			0			0	0
Other comprehensive income (loss)	(368)			(38)			(1,003)	(103)
Balance, end of period	(1,039)	(671)		5	43		(1,039)	5
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(40)		3	8		12	3	12
Net unrealized gains (losses)	(103)			0			(149)	(1)
Amounts reclassified from AOCI	4			(1)			7	(4)
Other comprehensive income (loss)	(99)			(1)			(142)	(5)
Balance, end of period	(139)	(40)		7	8		(139)	7
Pension and Post-retirement Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(252)		$ (255)	(254)		$ (260)	(255)	(260)
Net unrealized gains (losses)	0			(1)			0	1
Amounts reclassified from AOCI	3			2			6	6
Other comprehensive income (loss)	3			1			6	7
Balance, end of period	$ (249)	$ (252)		$ (253)	$ (254)		$ (249)	$ (253)