INVESTMENTS - Overview (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2023	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Investment Holdings
Total investments		$ 512,578		$ 526,582
Accrued interest receivable		2,000		2,000
Interest and dividends on investments
Taxable interest		4,000	$ 2,013
Interest exempt from U.S. federal income tax		85	5
Dividend income		59	32
Total interest and dividend income on investments		4,144	2,050
Gross realized investments losses, excluding losses from other-than-temporary impairment
Gross realized investment gains		88	153
Gross realized investment losses		(16)	(73)
Net realized gains (losses) on sales of investments		72	80
Debt securities AFS
Allowance for credit losses		4	$ 8	3	$ 8
Fair value		240,487		249,679
Transfer of investment securities from HTM to AFS, amortized cost	$ 3,300
Transfer of securities from HTM to AFS, unrealized gain	$ 100
Debt securities available-for-sale (AFS)
Investment Holdings
Total investments		240,487		249,679
Debt securities held-to-maturity (HTM)
Investment Holdings
Total investments		264,342		268,863
Mortgage-backed securities - U.S. government-sponsored agency guaranteed
Debt securities AFS
Amortized cost		15,193		12,009
Gross unrealized gains		98		8
Gross unrealized losses		675		755
Allowance for credit losses		0		0
Fair value		14,616		11,262
Residential mortgages
Debt securities AFS
Amortized cost		343		488
Gross unrealized gains		0		0
Gross unrealized losses		3		3
Allowance for credit losses		0		0
Fair value		340		485
Commercial
Debt securities AFS
Amortized cost		2		2
Gross unrealized gains		0		0
Gross unrealized losses		0		0
Allowance for credit losses		0		0
Fair value		2		2
Mortgage-backed securities
Debt securities AFS
Amortized cost		15,538		12,499
Gross unrealized gains		98		8
Gross unrealized losses		678		758
Allowance for credit losses		0		0
Fair value		14,958		11,749
U.S. Treasury
Debt securities AFS
Amortized cost		88,721		94,732
Gross unrealized gains		39		50
Gross unrealized losses		2,083		2,492
Allowance for credit losses		0		0
Fair value		86,677		92,290
Agency obligations
Debt securities AFS
Amortized cost		0		0
Gross unrealized gains		0		0
Gross unrealized losses		0		0
Allowance for credit losses		0		0
Fair value		0		0
U.S. Treasury and federal agency securities
Debt securities AFS
Amortized cost		88,721		94,732
Gross unrealized gains		39		50
Gross unrealized losses		2,083		2,492
Allowance for credit losses		0		0
Fair value		86,677		92,290
State and municipal
Debt securities AFS
Amortized cost		2,394		2,363
Gross unrealized gains		24		19
Gross unrealized losses		125		159
Allowance for credit losses		0		0
Fair value		2,293		2,223
Foreign government
Debt securities AFS
Amortized cost		126,996		135,648
Gross unrealized gains		617		569
Gross unrealized losses		2,529		2,940
Allowance for credit losses		0		0
Fair value		125,084		133,277
Corporate
Debt securities AFS
Amortized cost		5,470		5,146
Gross unrealized gains		15		19
Gross unrealized losses		230		246
Allowance for credit losses		4		3
Fair value		5,251		4,916
Asset-backed securities
Debt securities AFS
Amortized cost		1,059		1,022
Gross unrealized gains		8		12
Gross unrealized losses		2		4
Allowance for credit losses		0		0
Fair value		1,065		1,030
Other debt securities
Debt securities AFS
Amortized cost		5,162		4,198
Gross unrealized gains		1		1
Gross unrealized losses		4		5
Allowance for credit losses		0		0
Fair value		5,159		4,194
Debt securities AFS
Debt securities AFS
Amortized cost		245,340		255,608
Gross unrealized gains		802		678
Gross unrealized losses		5,651		6,604
Allowance for credit losses		4		3
Fair value		240,487		249,679
Fair value | Marketable equity securities carried at fair value
Investment Holdings
Total investments		443		429
Fair value | Non-marketable equity securities
Investment Holdings
Total investments		444		466
Fair value | Non-marketable securities measured using measurement alternative
Investment Holdings
Total investments		1,619		1,676
Non-marketable equity securities measured using the measurement alternative		29		27
Carried at cost | Non-marketable equity securities
Investment Holdings
Total investments		$ 5,243		$ 5,469