Investment Securities - Schedule of Marketable Securities (Details) - USD ($)	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	$ 56,753,000,000	$ 44,853,000,000
Available for sale, gross unrealized gains	293,000,000	209,000,000
Available for sale, gross unrealized losses	193,000,000	536,000,000
Available-for-sale, fair value	56,853,000,000	44,526,000,000
Held to maturity, amortized cost	49,477,000,000	57,117,000,000
Investment securities held-to-maturity	44,925,000,000	51,503,000,000
Allowance for credit losses on available-for-sale securities	0	0	$ 0	$ 0	$ 2,000,000
Direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	19,146,000,000	8,427,000,000
Available for sale, gross unrealized gains	38,000,000	39,000,000
Available for sale, gross unrealized losses	60,000,000	165,000,000
Available-for-sale, fair value	19,124,000,000	8,301,000,000
Held to maturity, amortized cost	5,589,000,000	8,584,000,000
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	64,000,000	163,000,000
Investment securities held-to-maturity	5,525,000,000	8,421,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	11,270,000,000	10,870,000,000
Available for sale, gross unrealized gains	78,000,000	49,000,000
Available for sale, gross unrealized losses	88,000,000	164,000,000
Available-for-sale, fair value	11,260,000,000	10,755,000,000
Held to maturity, amortized cost	36,951,000,000	39,472,000,000
Held to maturity, gross unrealized gains	13,000,000	7,000,000
Held to maturity, gross unrealized losses	4,411,000,000	5,271,000,000
Investment securities held-to-maturity	32,553,000,000	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	30,416,000,000	19,297,000,000
Available for sale, gross unrealized gains	116,000,000	88,000,000
Available for sale, gross unrealized losses	148,000,000	329,000,000
Available-for-sale, fair value	30,384,000,000	19,056,000,000
Held to maturity, amortized cost	42,540,000,000	48,056,000,000
Held to maturity, gross unrealized gains	13,000,000	7,000,000
Held to maturity, gross unrealized losses	4,475,000,000	5,434,000,000
Investment securities held-to-maturity	38,078,000,000	42,629,000,000
Mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,536,000,000	1,861,000,000
Available for sale, gross unrealized gains	4,000,000	3,000,000
Available for sale, gross unrealized losses	3,000,000	7,000,000
Available-for-sale, fair value	2,537,000,000	1,857,000,000
Asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,289,000,000	2,148,000,000
Available for sale, gross unrealized gains	6,000,000	2,000,000
Available for sale, gross unrealized losses	2,000,000	13,000,000
Available-for-sale, fair value	2,293,000,000	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	15,225,000,000	15,159,000,000
Available for sale, gross unrealized gains	98,000,000	73,000,000
Available for sale, gross unrealized losses	34,000,000	132,000,000
Available-for-sale, fair value	15,289,000,000	15,100,000,000
Held to maturity, amortized cost	4,332,000,000	5,757,000,000
Held to maturity, gross unrealized gains	9,000,000	8,000,000
Held to maturity, gross unrealized losses	77,000,000	153,000,000
Investment securities held-to-maturity	4,264,000,000	5,612,000,000
Other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,842,000,000	2,733,000,000
Available for sale, gross unrealized gains	58,000,000	39,000,000
Available for sale, gross unrealized losses	4,000,000	37,000,000
Available-for-sale, fair value	2,896,000,000	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	22,892,000,000	21,901,000,000
Available for sale, gross unrealized gains	166,000,000	117,000,000
Available for sale, gross unrealized losses	43,000,000	189,000,000
Available-for-sale, fair value	23,015,000,000	21,829,000,000
Held to maturity, amortized cost	4,332,000,000	5,757,000,000
Held to maturity, gross unrealized gains	9,000,000	8,000,000
Held to maturity, gross unrealized losses	77,000,000	153,000,000
Investment securities held-to-maturity	4,264,000,000	5,612,000,000
Student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	91,000,000	113,000,000
Available for sale, gross unrealized gains	2,000,000	1,000,000
Available for sale, gross unrealized losses	0	0
Available-for-sale, fair value	93,000,000	114,000,000
Held to maturity, amortized cost	2,605,000,000	3,298,000,000
Held to maturity, gross unrealized gains	5,000,000	2,000,000
Held to maturity, gross unrealized losses	27,000,000	62,000,000
Investment securities held-to-maturity	2,583,000,000	3,238,000,000
Collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,054,000,000	2,530,000,000
Available for sale, gross unrealized gains	4,000,000	3,000,000
Available for sale, gross unrealized losses	0	6,000,000
Available-for-sale, fair value	3,058,000,000	2,527,000,000
Non-agency CMBS and RMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	1,000,000	252,000,000
Available for sale, gross unrealized gains	4,000,000	0
Available for sale, gross unrealized losses	0	3,000,000
Available-for-sale, fair value	5,000,000	249,000,000
Held to maturity, amortized cost	0	6,000,000
Held to maturity, gross unrealized gains	0	18,000,000
Held to maturity, gross unrealized losses	0	0
Investment securities held-to-maturity	0	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	3,236,000,000	2,985,000,000
Available for sale, gross unrealized gains	11,000,000	4,000,000
Available for sale, gross unrealized losses	0	9,000,000
Available-for-sale, fair value	3,247,000,000	2,980,000,000
Held to maturity, amortized cost	2,605,000,000	3,304,000,000
Held to maturity, gross unrealized gains	5,000,000	20,000,000
Held to maturity, gross unrealized losses	27,000,000	62,000,000
Investment securities held-to-maturity	2,583,000,000	3,262,000,000
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	151,000,000	356,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	1,000,000
Available-for-sale, fair value	151,000,000	355,000,000
Other U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	58,000,000	314,000,000
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	2,000,000	8,000,000
Available-for-sale, fair value	56,000,000	306,000,000
Including MMLF
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Held to maturity, amortized cost	49,477,000,000	57,117,000,000
Held to maturity, gross unrealized gains	27,000,000	35,000,000
Held to maturity, gross unrealized losses	4,579,000,000	5,649,000,000
Investment securities held-to-maturity	44,925,000,000	51,503,000,000
Agency CMBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	4,810,000,000	5,540,000,000
Held to maturity, amortized cost	5,190,000,000	5,230,000,000
Agency MBS
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	6,450,000,000	5,210,000,000
Non-US collateralized loan obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	890,000,000	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	$ 2,590,000,000	2,360,000,000
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	$ 60,000,000.00	$ 310,000,000