Securities - Available for Sale Securities (Unrealized Loss Position) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 36,873	$ 29,680
Temporarily impaired securities, gross unrealized losses, less than 12 months	2,688	568
Temporarily impaired securities, fair value, 12 months or longer	10,669	5,511
Temporarily impaired securities, gross unrealized losses, 12 months or longer	1,805	316
Temporarily impaired securities, fair value	47,542	35,191
Temporarily impaired securities, gross unrealized losses	4,493	884
U.S. Treasury, agencies and corporations
Securities available for sale:
Fair value, less than 12 months	9,005	9,078
Gross unrealized losses, less than 12 months	468	98
Fair value, 12 months or longer	584	243
Gross unrealized losses, 12 months or longer	23	3
Fair value	9,589	9,321
Gross unrealized losses	491	101
Agency residential collateralized mortgage obligations
Securities available for sale:
Fair value, less than 12 months	14,387	12,603
Gross unrealized losses, less than 12 months	1,460	315
Fair value, 12 months or longer	4,563	1,255
Gross unrealized losses, 12 months or longer	915	95
Fair value	18,950	13,858
Gross unrealized losses	2,375	410
Held-to-maturity securities:
Fair value, less than 12 months	2,565	96
Gross unrealized losses, less than 12 months	100	0
Fair value, 12 months or longer	0	0
Gross unrealized losses, 12 months or longer	0	0
Fair value	2,565	96
Gross unrealized losses	100	0
Agency residential mortgage-backed securities
Held-to-maturity securities:
Fair value, less than 12 months	137
Gross unrealized losses, less than 12 months	7
Fair value, 12 months or longer	0
Gross unrealized losses, 12 months or longer	0
Fair value	137
Gross unrealized losses	7
Agency residential mortgage-backed securities | Maximum
Held-to-maturity securities:
Gross unrealized losses		1
Agency residential mortgage-backed securities | Mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	3,053	3,793
Gross unrealized losses, less than 12 months	334	49
Fair value, 12 months or longer	1,014	178
Gross unrealized losses, 12 months or longer	180	3
Fair value	4,067	3,971
Gross unrealized losses	514	52
Agency commercial mortgage-backed securities
Securities available for sale:
Fair value, less than 12 months	3,647	1,645
Gross unrealized losses, less than 12 months	115	75
Fair value, 12 months or longer	4,504	3,834
Gross unrealized losses, 12 months or longer	686	215
Fair value	8,151	5,479
Gross unrealized losses	801	290
Held-to-maturity securities:
Fair value, less than 12 months	2,317
Gross unrealized losses, less than 12 months	90
Fair value, 12 months or longer	0
Gross unrealized losses, 12 months or longer	0
Fair value	2,317
Gross unrealized losses	90
Asset-backed securities
Held-to-maturity securities:
Fair value, less than 12 months	1,755	2,450
Gross unrealized losses, less than 12 months	114	31
Fair value, 12 months or longer	1	1
Gross unrealized losses, 12 months or longer	0	0
Fair value	1,756	2,451
Gross unrealized losses	114	31
Asset-backed securities | Maximum
Held-to-maturity securities:
Gross unrealized losses	1
Other securities
Held-to-maturity securities:
Fair value, less than 12 months	7	15
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	3	0
Gross unrealized losses, 12 months or longer	1	0
Fair value	10	15
Gross unrealized losses	$ 1	$ 0