Investment Securities - Fair Value and Gross Unrealized Losses by Aging Category (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Available-for-sale securities
Less than 12 months, Fair value	$ 30,160	$ 16,538
Less than 12 months, Gross unrealized losses	530	65
12 months or more, Fair Value	2,826	1,336
12 months or more, Gross unrealized losses	118	42
Total fair value	32,986	17,874
Total gross unrealized losses	648	107
Total mortgage-backed securities
Available-for-sale securities
Less than 12 months, Fair value	8,348	2,993
Less than 12 months, Gross unrealized losses	130	7
12 months or more, Fair Value	378	394
12 months or more, Gross unrealized losses	23	13
Total fair value	8,726	3,387
Total gross unrealized losses	153	20
U.S. GSEs and government agencies
Available-for-sale securities
Total fair value	9,800	2,200
Residential: U.S.
Available-for-sale securities
Less than 12 months, Fair value	1,593	303
Less than 12 months, Gross unrealized losses	38	1
12 months or more, Fair Value	42	45
12 months or more, Gross unrealized losses	1	1
Total fair value	1,635	348
Total gross unrealized losses	39	2
Residential: Non-U.S.
Available-for-sale securities
Less than 12 months, Fair value	2,349	133
Less than 12 months, Gross unrealized losses	6	1
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	2,349	133
Total gross unrealized losses	6	1
Commercial
Available-for-sale securities
Less than 12 months, Fair value	4,406	2,557
Less than 12 months, Gross unrealized losses	86	5
12 months or more, Fair Value	336	349
12 months or more, Gross unrealized losses	22	12
Total fair value	4,742	2,906
Total gross unrealized losses	108	17
Obligations of U.S. states and municipalities
Available-for-sale securities
Less than 12 months, Fair value	1,456	120
Less than 12 months, Gross unrealized losses	152	2
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	1,456	120
Total gross unrealized losses	152	2
Non-U.S. government debt securities
Available-for-sale securities
Less than 12 months, Fair value	8,631	5,060
Less than 12 months, Gross unrealized losses	157	37
12 months or more, Fair Value	916	510
12 months or more, Gross unrealized losses	63	9
Total fair value	9,547	5,570
Total gross unrealized losses	220	46
Corporate debt securities
Available-for-sale securities
Less than 12 months, Fair value	264	166
Less than 12 months, Gross unrealized losses	3	1
12 months or more, Fair Value	45	46
12 months or more, Gross unrealized losses	17	18
Total fair value	309	212
Total gross unrealized losses	20	19
Asset-backed securities: Collateralized loan obligations
Available-for-sale securities
Less than 12 months, Fair value	8,561	8,110
Less than 12 months, Gross unrealized losses	73	18
12 months or more, Fair Value	1,331	208
12 months or more, Gross unrealized losses	12	0
Total fair value	9,892	8,318
Total gross unrealized losses	85	18
Asset-backed securities: Other
Available-for-sale securities
Less than 12 months, Fair value	2,900	89
Less than 12 months, Gross unrealized losses	15	0
12 months or more, Fair Value	156	178
12 months or more, Gross unrealized losses	3	2
Total fair value	3,056	267
Total gross unrealized losses	$ 18	$ 2