INVESTMENTS - Available-for-sale Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 68,136	$ 59,278
Allowance for Credit Losses	13	0
Gross Unrealized Gains	8,338	3,465
Gross Unrealized Losses	108	381
Fair Value	76,353	62,362
Amortized Cost
Due in one year or less, Amortized Cost	3,342
Due in years two through five, Amortized Cost	15,037
Due in years six through ten, Amortized Cost	17,786
Due after ten years, Amortized Cost	26,460
Subtotal	62,625
Amortized cost	68,123
Fair Value
Due in one year or less	3,362
Due in years two through five	16,026
Due in years six through ten	19,607
Due after ten years	31,727
Subtotal	70,722
Fair Value	76,353
Available For Sale Fixed Maturities Proceeds Gross Gains And Gross Losses From Sales And Other Than Temporary Impairments [Abstract]
Proceeds from sales	12,670	8,702	$ 7,136
Gross gains on sales	854	229	145
Gross losses on sales	(34)	(28)	(103)
Credit losses	(13)	0	(37)
Fixed Maturities - Credit Loss Impairments
Balances, beginning of period	15	46
Previously recognized impairments on securities that matured, paid, prepaid or sold	0	(31)
Recognized impairments on securities impaired to fair value this period	0	0
Credit losses recognized this period on securities for which credit losses were not previously recognized	6	0
Additional credit losses this period on securities previously impaired	7	0
Increases due to passage of time on previously recorded credit losses	0	0
Accretion of previously recognized impairments due to increases in expected cash flows (for OTTI securities 2019 and prior)	0	0
Balances, end of period	28	15	$ 46
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	48,501	42,347
Allowance for Credit Losses	13	0
Gross Unrealized Gains	4,703	2,178
Gross Unrealized Losses	89	61
Fair Value	53,102	44,464
U.S. Treasury, government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,644	14,385
Allowance for Credit Losses	0	0
Gross Unrealized Gains	3,304	1,151
Gross Unrealized Losses	5	305
Fair Value	15,943	15,231
States and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	482	584
Allowance for Credit Losses	0	0
Gross Unrealized Gains	92	68
Gross Unrealized Losses	0	3
Fair Value	574	649
Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,011	460
Allowance for Credit Losses	0	0
Gross Unrealized Gains	98	35
Gross Unrealized Losses	6	5
Fair Value	1,103	490
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	119	161
Allowance for Credit Losses	0	0
Gross Unrealized Gains	12	12
Gross Unrealized Losses	0	0
Fair Value	131	173
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	119
Fair Value
Without single maturity date	131
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,633	843
Allowance for Credit Losses	0	0
Gross Unrealized Gains	28	3
Gross Unrealized Losses	5	2
Fair Value	3,656	844
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	3,633
Fair Value
Without single maturity date	3,656
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,148
Allowance for Credit Losses	0
Gross Unrealized Gains	55
Gross Unrealized Losses	0
Fair Value	1,203
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	1,148
Fair Value
Without single maturity date	1,203
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	598	498
Allowance for Credit Losses	0	0
Gross Unrealized Gains	46	18
Gross Unrealized Losses	3	5
Fair Value	641	$ 511
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	598
Fair Value
Without single maturity date	$ 641