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INVESTMENTS - Debt Securities Held-to-Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Held-to-maturity (HTM) debt securities
Amortized cost, net	$ 206,094		$ 242,382
Gross unrealized gains	144		133
Gross unrealized losses	14,102		18,105
Fair value	192,136		224,410
Allowance for credit losses on HTM debt securities	136	$ 130	137	$ 99	$ 106	$ 95
Mortgage-backed securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	70,448		73,789
Gross unrealized gains	21		12
Gross unrealized losses	8,743		10,442
Fair value	61,726		63,359
U.S. government-sponsored agency guaranteed
Held-to-maturity (HTM) debt securities
Amortized cost, net	69,227		72,542
Gross unrealized gains	1		0
Gross unrealized losses	8,617		10,291
Fair value	60,611		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	1,221		1,247
Gross unrealized gains	20		12
Gross unrealized losses	126		151
Fair value	1,115		1,108
U.S. treasury securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	94,987		126,142
Gross unrealized gains	0		0
Gross unrealized losses	4,509		6,934
Fair value	90,478		119,208
State and municipal
Held-to-maturity (HTM) debt securities
Amortized cost, net	8,780		8,903
Gross unrealized gains	16		27
Gross unrealized losses	793		668
Fair value	8,003		8,262
Foreign government
Held-to-maturity (HTM) debt securities
Amortized cost, net	747		988
Gross unrealized gains	19		3
Gross unrealized losses	0		0
Fair value	766		991
Asset-backed securities
Held-to-maturity (HTM) debt securities
Amortized cost, net	31,132		32,560
Gross unrealized gains	88		91
Gross unrealized losses	57		61
Fair value	$ 31,163		$ 32,590