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INVESTMENTS - Debt Securities Held-to-Maturity (Details) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2023	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Held-to-maturity debt securities
Amortized cost, net		$ 259,456	$ 268,863
Gross unrealized gains		10	101
Gross unrealized losses		28,464	25,316
Fair value		231,002	243,648
Allowance for credit losses on HTM debt securities		95	120	$ 115
Transfer of securities from HTM to AFS, unrealized gain	$ 100
Mortgage-backed securities - U.S. government-sponsored agency guaranteed
Held-to-maturity debt securities
Amortized cost, net		81,442	90,063
Gross unrealized gains		0	58
Gross unrealized losses		13,354	10,033
Fair value		68,088	80,088
Mortgage-backed securities - Non-U.S. residential
Held-to-maturity debt securities
Amortized cost, net		330	445
Gross unrealized gains		0	0
Gross unrealized losses		0	0
Fair value		330	445
Commercial
Held-to-maturity debt securities
Amortized cost, net		1,133	1,114
Gross unrealized gains		0	5
Gross unrealized losses		169	1
Fair value		964	1,118
Mortgage-backed securities
Held-to-maturity debt securities
Amortized cost, net		82,905	91,622
Gross unrealized gains		0	63
Gross unrealized losses		13,523	10,034
Fair value		69,382	81,651
U.S. treasury securities
Held-to-maturity debt securities
Amortized cost, net		134,934	134,961
Gross unrealized gains		0	0
Gross unrealized losses		13,413	13,722
Fair value		121,521	121,239
State and municipal
Held-to-maturity debt securities
Amortized cost, net		9,103	9,237
Gross unrealized gains		9	34
Gross unrealized losses		1,188	764
Fair value		7,924	8,507
Foreign government
Held-to-maturity debt securities
Amortized cost, net		2,314	2,075
Gross unrealized gains		0	0
Gross unrealized losses		89	93
Fair value		2,225	1,982
Asset-backed securities
Held-to-maturity debt securities
Amortized cost, net		30,200	30,968
Gross unrealized gains		1	4
Gross unrealized losses		251	703
Fair value		$ 29,950	$ 30,269