INVESTMENTS - Available-for-sale Securities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 67,515		$ 67,515		$ 62,937
Allowance for Credit Losses	13		13		0
Gross Unrealized Gains	8,954		8,954		3,789
Gross Unrealized Losses	213		213		383
Fixed maturities available for sale, at fair value	76,243		76,243		66,343
Amortized Cost
Due in one year or less	4,645		4,645
Due in years two through five	15,141		15,141
Due in years six through ten	18,394		18,394
Due after ten years	25,870		25,870
Subtotal	64,050		64,050
Amortized cost	67,502		67,502
Fair Value
Due in one year or less	4,688		4,688
Due in years two through five	15,985		15,985
Due in years six through ten	20,398		20,398
Due after ten years	31,693		31,693
Subtotal	72,764		72,764
Fair Value	76,243		76,243
Fixed Maturities Proceeds Gross Gains And Gross Losses From Sales And Other Than Temporary Impairments [Abstract]
Proceeds from sales	2,947	$ 1,614	4,767	$ 3,064
Gross gains on sales	207	10	277	18
Gross losses on sales	(28)	(7)	(34)	(25)
Credit losses	(11)	0	(13)	0
Fixed Maturities - Credit Loss Impairments
Balances, beginning of period	(23)	(26)	(21)	(58)
Previously recognized impairments on securities that matured, paid, prepaid or sold	2	1	2	33
Recognized impairments on securities impaired to fair value this period	0	0	0	0
Impairments recognized this period on securities not previously impaired	(8)	0	(10)	0
Additional impairments this period on securities previously impaired	(3)	0	(3)	0
Increases due to passage of time on previously recorded credit losses	0	0	0	0
Accretion of previously recognized impairments due to increases in expected cash flows	0	0	0	0
Balances, end of period	(32)	$ (25)	(32)	$ (25)
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	49,494		49,494		45,900
Allowance for Credit Losses	13		13		0
Gross Unrealized Gains	4,452		4,452		2,361
Gross Unrealized Losses	156		156		62
Fixed maturities available for sale, at fair value	53,777		53,777		48,199
U.S. Treasury, government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	13,135		13,135		14,410
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	4,242		4,242		1,289
Gross Unrealized Losses	0		0		305
Fixed maturities available for sale, at fair value	17,377		17,377		15,394
States and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	663		663		638
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	112		112		70
Gross Unrealized Losses	0		0		3
Fixed maturities available for sale, at fair value	775		775		705
Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	771		771		462
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	69		69		35
Gross Unrealized Losses	5		5		5
Fixed maturities available for sale, at fair value	835		835		492
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	160		160		178
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	15		15		13
Gross Unrealized Losses	0		0		0
Fixed maturities available for sale, at fair value	175		175		191
Amortized Cost
Without single maturity date	160		160
Fair Value
Without single maturity date	175		175
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,062		2,062		848
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	24		24		4
Gross Unrealized Losses	41		41		3
Fixed maturities available for sale, at fair value	2,045		2,045		849
Amortized Cost
Without single maturity date	2,062		2,062
Fair Value
Without single maturity date	2,045		2,045
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	854		854
Allowance for Credit Losses	0		0
Gross Unrealized Gains	25		25
Gross Unrealized Losses	0		0
Fixed maturities available for sale, at fair value	879		879
Amortized Cost
Without single maturity date	854		854
Fair Value
Without single maturity date	879		879
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	376		376		501
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	15		15		17
Gross Unrealized Losses	11		11		5
Fixed maturities available for sale, at fair value	380		380		$ 513
Amortized Cost
Without single maturity date	376		376
Fair Value
Without single maturity date	$ 380		$ 380