Components of Other Comprehensive Income (Loss) - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 8,697	$ 8,494	$ 8,307	$ 8,307	$ 8,494	$ 8,307
Net unrealized gains (losses)	(256)		38		(680)	(63)
Amounts reclassified from AOCI	4		0		5	0
Other comprehensive income (loss)	(252)	(423)	38	(101)	(675)	(63)
Balance, end of period	8,551	8,697	8,565	8,307	8,551	8,565
Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(711)	(288)	(241)	(140)	(288)	(140)
Balance, end of period	(963)	(711)	(203)	(241)	(963)	(203)
Securities AFS
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(440)	(36)	5	108	(36)	108
Net unrealized gains (losses)	(231)		38		(635)	(65)
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income (loss)	(231)		38		(635)	(65)
Balance, end of period	(671)	(440)	43	5	(671)	43
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(18)	3	10	12	3	12
Net unrealized gains (losses)	(25)		0		(45)	(1)
Amounts reclassified from AOCI	3		(2)		2	(3)
Other comprehensive income (loss)	(22)		(2)		(43)	(4)
Balance, end of period	(40)	(18)	8	10	(40)	8
Pension and Post-retirement Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(253)	(255)	(256)	(260)	(255)	(260)
Net unrealized gains (losses)	0		0		0	3
Amounts reclassified from AOCI	1		2		3	3
Other comprehensive income (loss)	1		2		3	6
Balance, end of period	$ (252)	$ (253)	$ (254)	$ (256)	$ (252)	$ (254)