Investment Securities - Fair Value and Gross Unrealized Losses by Aging Category (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Available-for-sale securities
Less than 12 months, Fair value	$ 26,764	$ 10,737
Less than 12 months, Gross unrealized losses	482	49
12 months or more, Fair value	9,340	16,033
12 months or more, Gross unrealized losses	689	866
Total fair value	36,104	26,770
Total gross unrealized losses	1,171	915
Total mortgage-backed securities
Available-for-sale securities
Less than 12 months, Fair value	2,268	309
Less than 12 months, Gross unrealized losses	14	3
12 months or more, Fair value	2,139	3,657
12 months or more, Gross unrealized losses	106	205
Total fair value	4,407	3,966
Total gross unrealized losses	120	208
U.S. GSEs and government agencies
Available-for-sale securities
Total fair value	5,300	4,600
Residential: U.S.
Available-for-sale securities
Less than 12 months, Fair value	1,505	81
Less than 12 months, Gross unrealized losses	6	0
12 months or more, Fair value	925	1,160
12 months or more, Gross unrealized losses	44	68
Total fair value	2,430	1,241
Total gross unrealized losses	50	68
Residential: Non-U.S.
Available-for-sale securities
Less than 12 months, Fair value	0	0
Less than 12 months, Gross unrealized losses	0	0
12 months or more, Fair value	30	722
12 months or more, Gross unrealized losses	0	1
Total fair value	30	722
Total gross unrealized losses	0	1
Commercial
Available-for-sale securities
Less than 12 months, Fair value	763	228
Less than 12 months, Gross unrealized losses	8	3
12 months or more, Fair value	1,184	1,775
12 months or more, Gross unrealized losses	62	136
Total fair value	1,947	2,003
Total gross unrealized losses	70	139
Obligations of U.S. states and municipalities
Available-for-sale securities
Less than 12 months, Fair value	10,037	2,134
Less than 12 months, Gross unrealized losses	233	20
12 months or more, Fair value	2,412	2,278
12 months or more, Gross unrealized losses	301	246
Total fair value	12,449	4,412
Total gross unrealized losses	534	266
Non-U.S. government debt securities
Available-for-sale securities
Less than 12 months, Fair value	14,234	7,145
Less than 12 months, Gross unrealized losses	234	23
12 months or more, Fair value	4,184	4,987
12 months or more, Gross unrealized losses	270	336
Total fair value	18,418	12,132
Total gross unrealized losses	504	359
Corporate debt securities
Available-for-sale securities
Less than 12 months, Fair value	9	9
Less than 12 months, Gross unrealized losses	0	0
12 months or more, Fair value	30	79
12 months or more, Gross unrealized losses	1	28
Total fair value	39	88
Total gross unrealized losses	1	28
Asset-backed securities: Collateralized loan obligations
Available-for-sale securities
Less than 12 months, Fair value	2	932
Less than 12 months, Gross unrealized losses	0	2
12 months or more, Fair value	375	3,744
12 months or more, Gross unrealized losses	3	26
Total fair value	377	4,676
Total gross unrealized losses	3	28
Asset-backed securities: Other
Available-for-sale securities
Less than 12 months, Fair value	214	208
Less than 12 months, Gross unrealized losses	1	1
12 months or more, Fair value	200	1,288
12 months or more, Gross unrealized losses	8	25
Total fair value	414	1,496
Total gross unrealized losses	$ 9	$ 26