Investment Securities - Schedule of Marketable Securities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 71,669,000,000	$ 66,973,000,000
Available for sale, gross unrealized gains	174,000,000	278,000,000
Available for sale, gross unrealized losses	198,000,000	97,000,000
Available-for-sale, fair value	71,645,000,000	67,154,000,000
Held to maturity, amortized cost	36,732,000,000	38,171,000,000
Investment securities held-to-maturity	32,560,000,000	34,166,000,000
Allowance for credit losses on available-for-sale securities	0	0
Allowance for credit losses on HTM investment securities	1,000,000	1,000,000
Direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	24,982,000,000	23,210,000,000
Available for sale, gross unrealized gains	36,000,000	55,000,000
Available for sale, gross unrealized losses	10,000,000	5,000,000
Available-for-sale, fair value	25,008,000,000	23,260,000,000
Held to maturity, amortized cost	274,000,000	573,000,000
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	2,000,000	3,000,000
Investment securities held-to-maturity	272,000,000	570,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	16,516,000,000	15,550,000,000
Available for sale, gross unrealized gains	78,000,000	90,000,000
Available for sale, gross unrealized losses	75,000,000	54,000,000
Available-for-sale, fair value	16,519,000,000	15,586,000,000
Held to maturity, amortized cost	32,186,000,000	32,876,000,000
Held to maturity, gross unrealized gains	5,000,000	9,000,000
Held to maturity, gross unrealized losses	4,116,000,000	3,965,000,000
Investment securities held-to-maturity	28,075,000,000	28,920,000,000
Total U.S. Treasury and federal agencies
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	41,498,000,000	38,760,000,000
Available for sale, gross unrealized gains	114,000,000	145,000,000
Available for sale, gross unrealized losses	85,000,000	59,000,000
Available-for-sale, fair value	41,527,000,000	38,846,000,000
Held to maturity, amortized cost	32,460,000,000	33,449,000,000
Held to maturity, gross unrealized gains	5,000,000	9,000,000
Held to maturity, gross unrealized losses	4,118,000,000	3,968,000,000
Investment securities held-to-maturity	28,347,000,000	29,490,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,643,000,000	2,573,000,000
Available for sale, gross unrealized gains	3,000,000	6,000,000
Available for sale, gross unrealized losses	3,000,000	1,000,000
Available-for-sale, fair value	2,643,000,000	2,578,000,000
Asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,290,000,000	2,081,000,000
Available for sale, gross unrealized gains	4,000,000	5,000,000
Available for sale, gross unrealized losses	1,000,000	1,000,000
Available-for-sale, fair value	2,293,000,000	2,085,000,000
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	19,351,000,000	17,693,000,000
Available for sale, gross unrealized gains	29,000,000	73,000,000
Available for sale, gross unrealized losses	101,000,000	35,000,000
Available-for-sale, fair value	19,279,000,000	17,731,000,000
Held to maturity, amortized cost	2,084,000,000	2,461,000,000
Held to maturity, gross unrealized gains	0	4,000,000
Held to maturity, gross unrealized losses	35,000,000	31,000,000
Investment securities held-to-maturity	2,049,000,000	2,434,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,868,000,000	2,784,000,000
Available for sale, gross unrealized gains	23,000,000	42,000,000
Available for sale, gross unrealized losses	4,000,000	0
Available-for-sale, fair value	2,887,000,000	2,826,000,000
Total non-U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	27,152,000,000	25,131,000,000
Available for sale, gross unrealized gains	59,000,000	126,000,000
Available for sale, gross unrealized losses	109,000,000	37,000,000
Available-for-sale, fair value	27,102,000,000	25,220,000,000
Held to maturity, amortized cost	2,084,000,000	2,461,000,000
Held to maturity, gross unrealized gains	0	4,000,000
Held to maturity, gross unrealized losses	35,000,000	31,000,000
Investment securities held-to-maturity	2,049,000,000	2,434,000,000
Student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	37,000,000	63,000,000
Available for sale, gross unrealized gains	0	1,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	37,000,000	64,000,000
Held to maturity, amortized cost	2,188,000,000	2,261,000,000
Held to maturity, gross unrealized gains	3,000,000	5,000,000
Held to maturity, gross unrealized losses	27,000,000	24,000,000
Investment securities held-to-maturity	2,164,000,000	2,242,000,000
Collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,867,000,000	2,904,000,000
Available for sale, gross unrealized gains	0	2,000,000
Available for sale, gross unrealized losses	4,000,000	1,000,000
Available-for-sale, fair value	2,863,000,000	2,905,000,000
Non-agency CMBS and RMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	0	0
Available for sale, gross unrealized gains	0	3,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	0	3,000,000
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	2,994,000,000	3,057,000,000
Available for sale, gross unrealized gains	1,000,000	7,000,000
Available for sale, gross unrealized losses	4,000,000	1,000,000
Available-for-sale, fair value	2,991,000,000	3,063,000,000
Held to maturity, amortized cost	2,188,000,000	2,261,000,000
Held to maturity, gross unrealized gains	3,000,000	5,000,000
Held to maturity, gross unrealized losses	27,000,000	24,000,000
Investment securities held-to-maturity	2,164,000,000	2,242,000,000
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	25,000,000	25,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	25,000,000	25,000,000
Other U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available-for-sale, fair value		0
Including MMLF
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Held to maturity, amortized cost	36,732,000,000	38,171,000,000
Held to maturity, gross unrealized gains	8,000,000	18,000,000
Held to maturity, gross unrealized losses	4,180,000,000	4,023,000,000
Investment securities held-to-maturity	32,560,000,000	34,166,000,000
Agency CMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,490,000,000	2,810,000,000
Held to maturity, amortized cost	5,060,000,000.00	5,080,000,000.00
Agency MBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	14,030,000,000.00	12,780,000,000
Non-US collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	860,000,000	770,000,000
Non-U.S. debt securities, corporate bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 2,550,000,000	$ 2,400,000,000
Federal family education loan program
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Securities guaranteed by the federal government	97.00%