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INVESTMENTS - Debt Securities Held-to-Maturity (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Held-to-maturity (HTM) debt securities
Amortized cost, net	$ 220,385	$ 242,382
Gross unrealized gains	100	133
Gross unrealized losses	15,298	18,105
Fair value	205,187	224,410
Allowance for credit losses on HTM debt securities	130	137	$ 106	$ 95
Mortgage-backed securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	72,200	73,789
Gross unrealized gains	15	12
Gross unrealized losses	9,053	10,442
Fair value	63,162	63,359
U.S. government-sponsored agency guaranteed
Held-to-maturity (HTM) debt securities
Amortized cost, net	70,986	72,542
Gross unrealized gains	0	0
Gross unrealized losses	8,924	10,291
Fair value	62,062	62,251
Mortgage-backed securities - Non-U.S. residential
Held-to-maturity (HTM) debt securities
Amortized cost, net	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Fair value	0	0
Commercial
Held-to-maturity (HTM) debt securities
Amortized cost, net	1,214	1,247
Gross unrealized gains	15	12
Gross unrealized losses	129	151
Fair value	1,100	1,108
U.S. treasury securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	106,134	126,142
Gross unrealized gains	0	0
Gross unrealized losses	5,425	6,934
Fair value	100,709	119,208
State and municipal
Held-to-maturity (HTM) debt securities
Amortized cost, net	8,824	8,903
Gross unrealized gains	43	27
Gross unrealized losses	746	668
Fair value	8,121	8,262
Foreign government
Held-to-maturity (HTM) debt securities
Amortized cost, net	680	988
Gross unrealized gains	10	3
Gross unrealized losses	0	0
Fair value	690	991
Asset-backed securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	32,547	32,560
Gross unrealized gains	32	91
Gross unrealized losses	74	61
Fair value	$ 32,505	$ 32,590