Investment Securities - Schedule of Marketable Securities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 67,449,000,000	$ 59,006,000,000
Available for sale, gross unrealized gains	204,000,000	172,000,000
Available for sale, gross unrealized losses	209,000,000	283,000,000
Available-for-sale, fair value	67,444,000,000	58,895,000,000
Held to maturity, amortized cost	45,505,000,000	47,727,000,000
Investment securities held-to-maturity	40,424,000,000	41,906,000,000
Allowance for credit losses on available-for-sale securities	0	0
Allowance for credit losses on HTM investment securities	0	0	$ 1,000,000	$ 1,000,000
Direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	27,384,000,000	23,539,000,000
Available for sale, gross unrealized gains	33,000,000	38,000,000
Available for sale, gross unrealized losses	37,000,000	52,000,000
Available-for-sale, fair value	27,380,000,000	23,525,000,000
Held to maturity, amortized cost	4,418,000,000	5,417,000,000
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	34,000,000	55,000,000
Investment securities held-to-maturity	4,384,000,000	5,362,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	12,837,000,000	10,699,000,000
Available for sale, gross unrealized gains	36,000,000	21,000,000
Available for sale, gross unrealized losses	124,000,000	154,000,000
Available-for-sale, fair value	12,749,000,000	10,566,000,000
Held to maturity, amortized cost	35,355,000,000	36,101,000,000
Held to maturity, gross unrealized gains	7,000,000	2,000,000
Held to maturity, gross unrealized losses	4,980,000,000	5,677,000,000
Investment securities held-to-maturity	30,382,000,000	30,426,000,000
Total U.S. Treasury and federal agencies
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	40,221,000,000	34,238,000,000
Available for sale, gross unrealized gains	69,000,000	59,000,000
Available for sale, gross unrealized losses	161,000,000	206,000,000
Available-for-sale, fair value	40,129,000,000	34,091,000,000
Held to maturity, amortized cost	39,773,000,000	41,518,000,000
Held to maturity, gross unrealized gains	7,000,000	2,000,000
Held to maturity, gross unrealized losses	5,014,000,000	5,732,000,000
Investment securities held-to-maturity	34,766,000,000	35,788,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,466,000,000	2,426,000,000
Available for sale, gross unrealized gains	6,000,000	5,000,000
Available for sale, gross unrealized losses	1,000,000	1,000,000
Available-for-sale, fair value	2,471,000,000	2,430,000,000
Asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1,991,000,000	1,865,000,000
Available for sale, gross unrealized gains	6,000,000	5,000,000
Available for sale, gross unrealized losses	1,000,000	2,000,000
Available-for-sale, fair value	1,996,000,000	1,868,000,000
Non-U.S. sovereign, supranational and non-U.S. agency
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	16,027,000,000	13,954,000,000
Available for sale, gross unrealized gains	72,000,000	54,000,000
Available for sale, gross unrealized losses	40,000,000	69,000,000
Available-for-sale, fair value	16,059,000,000	13,939,000,000
Held to maturity, amortized cost	3,261,000,000	3,673,000,000
Held to maturity, gross unrealized gains	6,000,000	7,000,000
Held to maturity, gross unrealized losses	59,000,000	73,000,000
Investment securities held-to-maturity	3,208,000,000	3,607,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,089,000,000	2,787,000,000
Available for sale, gross unrealized gains	43,000,000	38,000,000
Available for sale, gross unrealized losses	3,000,000	4,000,000
Available-for-sale, fair value	3,129,000,000	2,821,000,000
Total non-U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	23,573,000,000	21,032,000,000
Available for sale, gross unrealized gains	127,000,000	102,000,000
Available for sale, gross unrealized losses	45,000,000	76,000,000
Available-for-sale, fair value	23,655,000,000	21,058,000,000
Held to maturity, amortized cost	3,261,000,000	3,673,000,000
Held to maturity, gross unrealized gains	6,000,000	7,000,000
Held to maturity, gross unrealized losses	59,000,000	73,000,000
Investment securities held-to-maturity	3,208,000,000	3,607,000,000
Student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	86,000,000	89,000,000
Available for sale, gross unrealized gains	1,000,000	1,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	87,000,000	90,000,000
Held to maturity, amortized cost	2,471,000,000	2,536,000,000
Held to maturity, gross unrealized gains	5,000,000	4,000,000
Held to maturity, gross unrealized losses	26,000,000	29,000,000
Investment securities held-to-maturity	2,450,000,000	2,511,000,000
Collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,393,000,000	3,447,000,000
Available for sale, gross unrealized gains	2,000,000	6,000,000
Available for sale, gross unrealized losses	2,000,000	0
Available-for-sale, fair value	3,393,000,000	3,453,000,000
Non-agency CMBS and RMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	0	1,000,000
Available for sale, gross unrealized gains	4,000,000	3,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	4,000,000	4,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	90,000,000	90,000,000
Available for sale, gross unrealized gains	1,000,000	1,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	91,000,000	91,000,000
Total asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,569,000,000	3,627,000,000
Available for sale, gross unrealized gains	8,000,000	11,000,000
Available for sale, gross unrealized losses	2,000,000	0
Available-for-sale, fair value	3,575,000,000	3,638,000,000
Held to maturity, amortized cost	2,471,000,000	2,536,000,000
Held to maturity, gross unrealized gains	5,000,000	4,000,000
Held to maturity, gross unrealized losses	26,000,000	29,000,000
Investment securities held-to-maturity	2,450,000,000	2,511,000,000
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	56,000,000	56,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	56,000,000	56,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	30,000,000	53,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	1,000,000	1,000,000
Available-for-sale, fair value	29,000,000	52,000,000
Including MMLF
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Held to maturity, amortized cost	45,505,000,000	47,727,000,000
Held to maturity, gross unrealized gains	18,000,000	13,000,000
Held to maturity, gross unrealized losses	5,099,000,000	5,834,000,000
Investment securities held-to-maturity	40,424,000,000	41,906,000,000
Agency CMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	4,260,000,000	4,360,000,000
Held to maturity, amortized cost	5,160,000,000	5,180,000,000
Agency MBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	8,490,000,000	6,200,000,000
Non-US collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	660,000,000	700,000,000
Non-U.S. debt securities, corporate bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 2,500,000,000	2,540,000,000
Federal family education loan program
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Federal government credit support guarantee, percentage minimum	97.00%
US debt securities, corporate bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 30,000,000.00	$ 50,000,000.00