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INVESTMENTS - Carrying Value and Fair Value of HTM Debt Securities by Contractual Maturity Dates (Details) - USD ($) $ in Millions	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Amortized cost
Total	$ 167,893		$ 189,831
Fair value
Total	157,524		179,520
Allowance for credit losses on HTM debt securities	117	$ 116	146	$ 136	$ 130	$ 137
Mortgage-backed securities
Amortized cost
Due within 1 year	35
After 1 but within 5 years	1,057
After 5 but within 10 years	1,376
After 10 years	61,543
Total	64,011		66,919
Fair value
Due within 1 year	35
After 1 but within 5 years	1,012
After 5 but within 10 years	1,296
After 10 years	54,340
Total	56,683		59,994
U.S. treasury securities
Amortized cost
Due within 1 year	30,345
After 1 but within 5 years	45,506
After 5 but within 10 years	0
After 10 years	0
Total	75,851		89,494
Fair value
Due within 1 year	30,051
After 1 but within 5 years	43,175
After 5 but within 10 years	0
After 10 years	0
Total	73,226		86,484
State and municipal
Amortized cost
Due within 1 year	6
After 1 but within 5 years	360
After 5 but within 10 years	2,460
After 10 years	5,557
Total	8,383		8,608
Fair value
Due within 1 year	6
After 1 but within 5 years	359
After 5 but within 10 years	2,370
After 10 years	5,223
Total	7,958		8,179
Foreign government
Amortized cost
Due within 1 year	640
After 1 but within 5 years	0
After 5 but within 10 years	0
After 10 years	0
Total	640		790
Fair value
Due within 1 year	656
After 1 but within 5 years	0
After 5 but within 10 years	0
After 10 years	0
Total	656		$ 810
All other
Amortized cost
Due within 1 year	0
After 1 but within 5 years	0
After 5 but within 10 years	1,647
After 10 years	17,361
Total	19,008
Fair value
Due within 1 year	0
After 1 but within 5 years	0
After 5 but within 10 years	1,647
After 10 years	17,354
Total	$ 19,001