INVESTMENTS - Debt Securities Held-to-Maturity (Details) - USD ($) $ in Millions	1 Months Ended
Jan. 31, 2023	Mar. 31, 2024	Dec. 31, 2023
Held-to-maturity debt securities
Amortized cost, net		$ 252,459	$ 254,247
Gross unrealized gains		83	91
Gross unrealized losses		21,168	19,337
Fair value		231,374	235,001
Allowance for credit losses on HTM debt securities		106	95
Transfer of securities from HTM to AFS, unrealized gain	$ 100
U.S. government-sponsored agency guaranteed
Held-to-maturity debt securities
Amortized cost, net		78,115	79,689
Gross unrealized gains		7	7
Gross unrealized losses		10,060	8,603
Fair value		68,062	71,093
Mortgage-backed securities - Non-U.S. residential
Held-to-maturity debt securities
Amortized cost, net		191	198
Gross unrealized gains		0	0
Gross unrealized losses		0	0
Fair value		191	198
Commercial Mortgage-Backed Securities
Held-to-maturity debt securities
Amortized cost, net		1,193	1,146
Gross unrealized gains		3	2
Gross unrealized losses		133	156
Fair value		1,063	992
Mortgage-backed securities
Held-to-maturity debt securities
Amortized cost, net		79,499	81,033
Gross unrealized gains		10	9
Gross unrealized losses		10,193	8,759
Fair value		69,316	72,283
U.S. treasury securities
Held-to-maturity debt securities
Amortized cost, net		131,767	131,776
Gross unrealized gains		0	0
Gross unrealized losses		10,264	9,908
Fair value		121,503	121,868
State and municipal
Held-to-maturity debt securities
Amortized cost, net		9,068	9,182
Gross unrealized gains		50	73
Gross unrealized losses		582	477
Fair value		8,536	8,778
Foreign government
Held-to-maturity debt securities
Amortized cost, net		2,262	2,210
Gross unrealized gains		0	0
Gross unrealized losses		48	58
Fair value		2,214	2,152
Asset-backed securities
Held-to-maturity debt securities
Amortized cost, net		29,863	30,046
Gross unrealized gains		23	9
Gross unrealized losses		81	135
Fair value		$ 29,805	$ 29,920

Amount, excluding accrued interest, of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount excluding accrued interest, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Amount, before tax and adjustment, of unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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