INVESTMENTS - Carrying Value and Fair Value of HTM Debt Securities by Contractual Maturity Dates (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Amortized cost, net	$ 251,125	$ 254,247
Held-to-maturity Securities, Debt Maturities, Fair Value;
Fair value	230,283	235,001
Allowance for credit losses on HTM debt securities	99	95
Mortgage-backed securities
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, amortized cost	34
After 1 but within 5 years, amortized cost	1,222
After 5 but within 10 years, amortized cost	590
After 10 years, amortized cost	75,741
Amortized cost, net	77,587	81,033
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	34
After 1 but within 5 years, fair value	1,151
After 5 but within 10 years, fair value	534
After 10 years, fair value	65,292
Fair value	67,011	72,283
U.S. treasury securities
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, amortized cost	36,532
After 1 but within 5 years, amortized cost	94,975
After 5 but within 10 years, amortized cost	0
After 10 years, amortized cost	0
Amortized cost, net	131,507	131,776
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	35,562
After 1 but within 5 years, fair value	86,328
After 5 but within 10 years, fair value	0
After 10 years, fair value	0
Fair value	121,890	121,868
State and municipal
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, amortized cost	33
After 1 but within 5 years, amortized cost	150
After 5 but within 10 years, amortized cost	1,502
After 10 years, amortized cost	7,314
Amortized cost, net	8,999	9,182
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	33
After 1 but within 5 years, fair value	149
After 5 but within 10 years, fair value	1,415
After 10 years, fair value	6,782
Fair value	8,379	8,778
Foreign government
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, amortized cost	1,792
After 1 but within 5 years, amortized cost	741
After 5 but within 10 years, amortized cost	0
After 10 years, amortized cost	0
Amortized cost, net	2,533	2,210
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	1,770
After 1 but within 5 years, fair value	734
After 5 but within 10 years, fair value	0
After 10 years, fair value	0
Fair value	2,504	$ 2,152
All other
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount;
Due within 1 year, amortized cost	0
After 1 but within 5 years, amortized cost	0
After 5 but within 10 years, amortized cost	12,529
After 10 years, amortized cost	17,970
Amortized cost, net	30,499
Held-to-maturity Securities, Debt Maturities, Fair Value;
Due within 1 year, fair value	0
After 1 but within 5 years, fair value	0
After 5 but within 10 years, fair value	12,546
After 10 years, fair value	17,953
Fair value	$ 30,499

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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