Investment Securities - Schedule of Marketable Securities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 48,957,000,000	$ 44,853,000,000
Available for sale, gross unrealized gains	146,000,000	209,000,000
Available for sale, gross unrealized losses	463,000,000	536,000,000
Available-for-sale, fair value	48,640,000,000	44,526,000,000
Held to maturity, amortized cost	52,914,000,000	57,117,000,000
Investment securities held-to-maturity	46,823,000,000	51,503,000,000
Allowance for credit losses on available-for-sale securities	0	0	$ 2,000,000	$ 2,000,000
Direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	11,831,000,000	8,427,000,000
Available for sale, gross unrealized gains	42,000,000	39,000,000
Available for sale, gross unrealized losses	144,000,000	165,000,000
Available-for-sale, fair value	11,729,000,000	8,301,000,000
Held to maturity, amortized cost	6,091,000,000	8,584,000,000
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	163,000,000	163,000,000
Investment securities held-to-maturity	5,928,000,000	8,421,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	11,208,000,000	10,870,000,000
Available for sale, gross unrealized gains	30,000,000	49,000,000
Available for sale, gross unrealized losses	149,000,000	164,000,000
Available-for-sale, fair value	11,089,000,000	10,755,000,000
Held to maturity, amortized cost	38,698,000,000	39,472,000,000
Held to maturity, gross unrealized gains	2,000,000	7,000,000
Held to maturity, gross unrealized losses	5,759,000,000	5,271,000,000
Investment securities held-to-maturity	32,941,000,000	34,208,000,000
Total U.S. Treasury and federal agencies
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	23,039,000,000	19,297,000,000
Available for sale, gross unrealized gains	72,000,000	88,000,000
Available for sale, gross unrealized losses	293,000,000	329,000,000
Available-for-sale, fair value	22,818,000,000	19,056,000,000
Held to maturity, amortized cost	44,789,000,000	48,056,000,000
Held to maturity, gross unrealized gains	2,000,000	7,000,000
Held to maturity, gross unrealized losses	5,922,000,000	5,434,000,000
Investment securities held-to-maturity	38,869,000,000	42,629,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1,961,000,000	1,861,000,000
Available for sale, gross unrealized gains	3,000,000	3,000,000
Available for sale, gross unrealized losses	4,000,000	7,000,000
Available-for-sale, fair value	1,960,000,000	1,857,000,000
Asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,168,000,000	2,148,000,000
Available for sale, gross unrealized gains	4,000,000	2,000,000
Available for sale, gross unrealized losses	7,000,000	13,000,000
Available-for-sale, fair value	2,165,000,000	2,137,000,000
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	15,410,000,000	15,159,000,000
Available for sale, gross unrealized gains	30,000,000	73,000,000
Available for sale, gross unrealized losses	119,000,000	132,000,000
Available-for-sale, fair value	15,321,000,000	15,100,000,000
Held to maturity, amortized cost	5,064,000,000	5,757,000,000
Held to maturity, gross unrealized gains	2,000,000	8,000,000
Held to maturity, gross unrealized losses	153,000,000	153,000,000
Investment securities held-to-maturity	4,913,000,000	5,612,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,690,000,000	2,733,000,000
Available for sale, gross unrealized gains	30,000,000	39,000,000
Available for sale, gross unrealized losses	29,000,000	37,000,000
Available-for-sale, fair value	2,691,000,000	2,735,000,000
Total non-U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	22,229,000,000	21,901,000,000
Available for sale, gross unrealized gains	67,000,000	117,000,000
Available for sale, gross unrealized losses	159,000,000	189,000,000
Available-for-sale, fair value	22,137,000,000	21,829,000,000
Held to maturity, amortized cost	5,064,000,000	5,757,000,000
Held to maturity, gross unrealized gains	2,000,000	8,000,000
Held to maturity, gross unrealized losses	153,000,000	153,000,000
Investment securities held-to-maturity	4,913,000,000	5,612,000,000
Student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	107,000,000	113,000,000
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	108,000,000	114,000,000
Held to maturity, amortized cost	3,055,000,000	3,298,000,000
Held to maturity, gross unrealized gains	4,000,000	2,000,000
Held to maturity, gross unrealized losses	42,000,000	62,000,000
Investment securities held-to-maturity	3,017,000,000	3,238,000,000
Collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,749,000,000	2,530,000,000
Available for sale, gross unrealized gains	4,000,000	3,000,000
Available for sale, gross unrealized losses	2,000,000	6,000,000
Available-for-sale, fair value	2,751,000,000	2,527,000,000
Non-agency CMBS and RMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	212,000,000	252,000,000
Available for sale, gross unrealized gains	1,000,000	0
Available for sale, gross unrealized losses	1,000,000	3,000,000
Available-for-sale, fair value	212,000,000	249,000,000
Held to maturity, amortized cost	6,000,000	6,000,000
Held to maturity, gross unrealized gains	18,000,000	18,000,000
Held to maturity, gross unrealized losses	0	0
Investment securities held-to-maturity	24,000,000	24,000,000
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	0
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	91,000,000	90,000,000
Total asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,158,000,000	2,985,000,000
Available for sale, gross unrealized gains	7,000,000	4,000,000
Available for sale, gross unrealized losses	3,000,000	9,000,000
Available-for-sale, fair value	3,162,000,000	2,980,000,000
Held to maturity, amortized cost	3,061,000,000	3,304,000,000
Held to maturity, gross unrealized gains	22,000,000	20,000,000
Held to maturity, gross unrealized losses	42,000,000	62,000,000
Investment securities held-to-maturity	3,041,000,000	3,262,000,000
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	343,000,000	356,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	3,000,000	1,000,000
Available-for-sale, fair value	340,000,000	355,000,000
Other U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	188,000,000	314,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	5,000,000	8,000,000
Available-for-sale, fair value	183,000,000	306,000,000
Including MMLF
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Held to maturity, amortized cost	52,914,000,000	57,117,000,000
Held to maturity, gross unrealized gains	26,000,000	35,000,000
Held to maturity, gross unrealized losses	6,117,000,000	5,649,000,000
Investment securities held-to-maturity	46,823,000,000	51,503,000,000
Non-US collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1,000,000,000	1,020,000,000.00
Non-U.S. debt securities, corporate bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,350,000,000	2,360,000,000
US debt securities, corporate bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 180,000,000	310,000,000
Federal family education loan program
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Federal government credit support guarantee, percentage minimum	97.00%
Agency CMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 5,240,000,000	5,540,000,000
Held to maturity, amortized cost	5,210,000,000	5,230,000,000
Agency MBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 5,850,000,000	$ 5,210,000,000