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INVESTMENTS - Debt Securities Held-to-Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Held-to-maturity (HTM) debt securities
Total	$ 167,893		$ 189,831
Gross unrealized gains	105		156
Gross unrealized losses	10,474		10,467
Fair value	157,524		179,520
Allowance for credit losses on HTM debt securities	117	$ 116	146	$ 136	$ 130	$ 137
Other
Held-to-maturity (HTM) debt securities
Total	1,349		1,288
Gross unrealized gains	17		21
Gross unrealized losses	117		115
Fair value	1,249		1,194
Mortgage-backed securities
Held-to-maturity (HTM) debt securities
Total	64,011		66,919
Gross unrealized gains	20		24
Gross unrealized losses	7,348		6,949
Fair value	56,683		59,994
U.S. government-sponsored agency guaranteed
Held-to-maturity (HTM) debt securities
Total	62,662		65,631
Gross unrealized gains	3		3
Gross unrealized losses	7,231		6,834
Fair value	55,434		58,800
U.S. treasury securities
Held-to-maturity (HTM) debt securities
Total	75,851		89,494
Gross unrealized gains	0		0
Gross unrealized losses	2,625		3,010
Fair value	73,226		86,484
State and municipal
Held-to-maturity (HTM) debt securities
Total	8,383		8,608
Gross unrealized gains	31		40
Gross unrealized losses	456		469
Fair value	7,958		8,179
Foreign government
Held-to-maturity (HTM) debt securities
Total	640		790
Gross unrealized gains	16		20
Gross unrealized losses	0		0
Fair value	656		810
Asset-backed securities
Held-to-maturity (HTM) debt securities
Total	19,008		24,020
Gross unrealized gains	38		72
Gross unrealized losses	45		39
Fair value	$ 19,001		$ 24,053