INVESTMENTS - Fair Value of AFS Debt Securities by Contractual Maturity Date (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Available for Sale Securities, Debt Maturities, Amortized Cost
Total amortized cost	$ 259,676
Available for Sale Securities, Debt Maturities, Fair Value
Total fair value	$ 256,936	$ 249,679
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Total	4.01%
Unallocated portfolio layer cumulative basis adjustments	$ 93
Mortgage-backed securities
Available for Sale Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	10
After 1 but within 5 years, amortized cost	570
After 5 but within 10 years, amortized cost	552
After 10 years, amortized cost	29,326
Total amortized cost	30,458
Available for Sale Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	11
After 1 but within 5 years, fair value	559
After 5 but within 10 years, fair value	528
After 10 Years, fair value	29,041
Total fair value	$ 30,139	11,749
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	1.48%
After 1 but within 5 years, weighted average yield	3.14%
After 5 but within 10 years, weighted average yield	3.64%
After 10 Years, weighted average yield	4.76%
Total	4.71%
U.S. Treasury and federal agency securities
Available for Sale Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	$ 45,716
After 1 but within 5 years, amortized cost	35,439
After 5 but within 10 years, amortized cost	529
After 10 years, amortized cost	0
Total amortized cost	81,684
Available for Sale Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	45,425
After 1 but within 5 years, fair value	34,449
After 5 but within 10 years, fair value	487
After 10 Years, fair value	0
Total fair value	$ 80,361	92,290
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	2.19%
After 1 but within 5 years, weighted average yield	1.25%
After 5 but within 10 years, weighted average yield	3.61%
After 10 Years, weighted average yield	0.00%
Total	1.79%
State and municipal
Available for Sale Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	$ 12
After 1 but within 5 years, amortized cost	132
After 5 but within 10 years, amortized cost	272
After 10 years, amortized cost	1,788
Total amortized cost	2,204
Available for Sale Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	11
After 1 but within 5 years, fair value	131
After 5 but within 10 years, fair value	269
After 10 Years, fair value	1,720
Total fair value	$ 2,131	2,223
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	1.39%
After 1 but within 5 years, weighted average yield	3.28%
After 5 but within 10 years, weighted average yield	4.04%
After 10 Years, weighted average yield	3.82%
Total	3.81%
Foreign government
Available for Sale Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	$ 63,008
After 1 but within 5 years, amortized cost	64,760
After 5 but within 10 years, amortized cost	3,781
After 10 years, amortized cost	496
Total amortized cost	132,045
Available for Sale Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	62,733
After 1 but within 5 years, fair value	64,238
After 5 but within 10 years, fair value	3,765
After 10 Years, fair value	462
Total fair value	$ 131,198	133,277
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	5.24%
After 1 but within 5 years, weighted average yield	5.26%
After 5 but within 10 years, weighted average yield	3.95%
After 10 Years, weighted average yield	2.61%
Total	5.20%
All other
Available for Sale Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	$ 6,408
After 1 but within 5 years, amortized cost	6,042
After 5 but within 10 years, amortized cost	766
After 10 years, amortized cost	69
Total amortized cost	13,285
Available for Sale Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	6,395
After 1 but within 5 years, fair value	5,913
After 5 but within 10 years, fair value	772
After 10 Years, fair value	27
Total fair value	$ 13,107
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	1.86%
After 1 but within 5 years, weighted average yield	5.70%
After 5 but within 10 years, weighted average yield	13.01%
After 10 Years, weighted average yield	1.34%
Total	4.25%
Debt securities
Available for Sale Securities, Debt Maturities, Fair Value
Total fair value	$ 256,936	$ 249,679
Available for Sale Securities, Debt Maturities, Weighted Average Yield
Unallocated portfolio layer cumulative basis adjustments	$ 200

Debt Securities, Available for sale, Amortized Cost, after Allowance for Credit Loss, Maturity

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, in portfolio layer hedging relationship.

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