INVESTMENTS - Available-for-sale Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 65,044		$ 62,937
Allowance for Credit Losses	2		0
Gross Unrealized Gains	6,297		3,789
Gross Unrealized Losses	1,018		383
Fixed maturities available for sale, at fair value	70,321		66,343
Amortized Cost
Due in one year or less	4,680
Due in years two through five	14,638
Due in years six through ten	18,606
Due after ten years	24,852
Subtotal	62,776
Amortized cost	65,042
Fair Value
Due in one year or less	4,675
Due in years two through five	14,733
Due in years six through ten	19,091
Due after ten years	29,679
Subtotal	68,178
Fair Value	70,321
Fixed Maturities Proceeds Gross Gains And Gross Losses From Sales And Other Than Temporary Impairments [Abstract]
Proceeds from sales	1,820	$ 1,450
Gross gains on sales	70	8
Gross losses on sales	(6)	(18)
Total OTTI	(2)	0
Fixed Maturities - Credit Loss Impairments
Balances, beginning of period	(21)	(58)
Previously recognized impairments on securities that matured, paid, prepaid or sold	0	32
Recognized impairments on securities impaired to fair value this period	0	0
Impairments recognized this period on securities not previously impaired	(2)	0
Additional impairments this period on securities previously impaired	0	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	0	0
Balances, end of period	(23)	$ (26)
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	47,408		45,900
Allowance for Credit Losses	2		0
Gross Unrealized Gains	1,760		2,361
Gross Unrealized Losses	844		62
Fixed maturities available for sale, at fair value	48,322		48,199
U.S. Treasury, government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14,226		14,410
Allowance for Credit Losses	0		0
Gross Unrealized Gains	4,407		1,289
Gross Unrealized Losses	0		305
Fixed maturities available for sale, at fair value	18,633		15,394
States and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	661		638
Allowance for Credit Losses	0		0
Gross Unrealized Gains	71		70
Gross Unrealized Losses	7		3
Fixed maturities available for sale, at fair value	725		705
Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	483		462
Allowance for Credit Losses	0		0
Gross Unrealized Gains	27		35
Gross Unrealized Losses	12		5
Fixed maturities available for sale, at fair value	498		492
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	170		178
Allowance for Credit Losses	0		0
Gross Unrealized Gains	14		13
Gross Unrealized Losses	0		0
Fixed maturities available for sale, at fair value	184		191
Amortized Cost
Without single maturity date	170
Fair Value
Without single maturity date	184
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,514		848
Allowance for Credit Losses	0		0
Gross Unrealized Gains	6		4
Gross Unrealized Losses	124		3
Fixed maturities available for sale, at fair value	1,396		849
Amortized Cost
Without single maturity date	1,514
Fair Value
Without single maturity date	1,396
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	37
Allowance for Credit Losses	0
Gross Unrealized Gains	2
Gross Unrealized Losses	0
Fixed maturities available for sale, at fair value	39
Amortized Cost
Without single maturity date	37
Fair Value
Without single maturity date	39
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	545		501
Allowance for Credit Losses	0		0
Gross Unrealized Gains	10		17
Gross Unrealized Losses	31		5
Fixed maturities available for sale, at fair value	524		$ 513
Amortized Cost
Without single maturity date	545
Fair Value
Without single maturity date	$ 524