INVESTMENTS - Carrying Value and Fair Value of HTM Debt Securities by Contractual Maturity Dates (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Carrying value	$ 268,863	$ 216,963
Held-to-maturity Securities, Debt Maturities, Fair Value
Fair value	$ 243,648	$ 216,038
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Total	1.94%	1.65%
Allowance for credit losses on HTM debt securities	$ 120	$ 87	$ 86	$ 0
Mortgage-backed securities
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	27	152
After 1 but within 5 years, amortized cost	520	684
After 5 but within 10 years, amortized cost	1,496	1,655
After 10 years, amortized cost	89,579	63,200
Carrying value	91,622	65,691
Held-to-maturity Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	27	151
After 1 but within 5 years, fair value	505	725
After 5 but within 10 years, fair value	1,374	1,739
After 10 years, fair value	79,745	63,232
Fair value	$ 81,651	$ 65,847
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	2.93%	1.70%
After 1 but within 5 years, weighted average yield	3.84%	3.01%
After 5 but within 10 years, weighted average yield	2.74%	2.74%
After 10 years, weighted average yield	2.89%	2.55%
Total	2.90%	2.56%
Allowance for credit losses on HTM debt securities	$ 1	$ 6	3	0
US Treasury securities
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	3,148	0
After 1 but within 5 years, amortized cost	86,617	65,498
After 5 but within 10 years, amortized cost	45,196	46,321
After 10 years, amortized cost	0	0
Carrying value	134,961	111,819
Held-to-maturity Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	3,017	0
After 1 but within 5 years, fair value	79,104	64,516
After 5 but within 10 years, fair value	39,118	45,701
After 10 years, fair value	0	0
Fair value	$ 121,239	$ 110,217
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	0.18%	0.00%
After 1 but within 5 years, weighted average yield	1.04%	0.69%
After 5 but within 10 years, weighted average yield	1.16%	1.15%
After 10 years, weighted average yield	0.00%	0.00%
Total	1.06%	0.88%
State and municipal
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	$ 22	$ 51
After 1 but within 5 years, amortized cost	102	166
After 5 but within 10 years, amortized cost	1,002	908
After 10 years, amortized cost	8,111	7,798
Carrying value	9,237	8,923
Held-to-maturity Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	21	50
After 1 but within 5 years, fair value	100	170
After 5 but within 10 years, fair value	967	951
After 10 years, fair value	7,419	8,329
Fair value	$ 8,507	$ 9,500
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	2.73%	3.82%
After 1 but within 5 years, weighted average yield	2.99%	2.82%
After 5 but within 10 years, weighted average yield	3.16%	3.23%
After 10 years, weighted average yield	3.32%	2.65%
Total	3.30%	2.72%
Allowance for credit losses on HTM debt securities	$ 113	$ 75	74	0
Foreign government
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	143	292
After 1 but within 5 years, amortized cost	1,932	1,359
After 5 but within 10 years, amortized cost	0	0
After 10 years, amortized cost	0	0
Carrying value	2,075	1,651
Held-to-maturity Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	139	291
After 1 but within 5 years, fair value	1,843	1,328
After 5 but within 10 years, fair value	0	0
After 10 years, fair value	0	0
Fair value	$ 1,982	$ 1,619
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	10.83%	7.86%
After 1 but within 5 years, weighted average yield	9.94%	6.30%
After 5 but within 10 years, weighted average yield	0.00%	0.00%
After 10 years, weighted average yield	0.00%	0.00%
Total	10.00%	6.58%
Allowance for credit losses on HTM debt securities	$ 3	$ 4	$ 6	$ 0
All other
Held-to-maturity Securities, Debt Maturities, Amortized Cost
Due within 1 year, amortized cost	0	0
After 1 but within 5 years, amortized cost	0	0
After 5 but within 10 years, amortized cost	11,751	11,520
After 10 years, amortized cost	19,217	17,359
Carrying value	30,968	28,879
Held-to-maturity Securities, Debt Maturities, Fair Value
Due within 1 year, fair value	0	0
After 1 but within 5 years, fair value	0	0
After 5 but within 10 years, fair value	11,583	11,515
After 10 years, fair value	18,686	17,340
Fair value	$ 30,269	$ 28,855
Held-to-maturity Securities, Debt Maturities, Weighted Average Yield
Due within 1 year, weighted average yield	0.00%	0.00%
After 1 but within 5 years, weighted average yield	0.00%	0.00%
After 5 but within 10 years, weighted average yield	2.81%	2.78%
After 10 years, weighted average yield	1.53%	1.34%
Total	2.02%	1.92%