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	$ 63,615		$ 63,615		$ 59,278
Allowance for Credit Losses	13		13		0
Gross Unrealized Gains	8,431		8,431		3,465
Gross Unrealized Losses	211		211		381
Fair Value	71,822		71,822		62,362
Amortized Cost
Due in one year or less, Amortized Cost	4,393		4,393
Due in years two through five, Amortized Cost	14,167		14,167
Due in years six through ten, Amortized Cost	16,475		16,475
Due after ten years, Amortized Cost	25,138		25,138
Subtotal	60,173		60,173
Amortized cost	63,602		63,602
Fair Value
Due in one year or less, Fair Value	4,433		4,433
Due in years two through five, Fair Value	14,944		14,944
Due in years six through ten, Fair Value	18,256		18,256
Due after ten years, Fair Value	30,735		30,735
Subtotal	68,368		68,368
Fair Value	71,822		71,822
Available For Sale Fixed Maturities Proceeds Gross Gains And Gross Losses From Sales And Other Than Temporary Impairments [Abstract]
Proceeds from sales	2,864	$ 1,556	4,586	$ 2,917
Gross gains on sales	205	9	274	17
Gross losses on sales	(24)	(6)	(27)	(21)
Credit losses	(11)	0	(13)	0
Fixed Maturities - Credit Loss Impairments
Balances, beginning of period	(17)	(18)	(15)	(46)
Previously recognized impairments on securities that matured, paid, prepaid or sold	0	0	0	28
Recognized impairments on securities impaired to fair value this period	0	0	0	0
Credit losses recognized this period on securities for which credit losses were not previously recognized	(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	(28)	$ (18)	(28)	$ (18)
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,706		45,706		42,347
Allowance for Credit Losses	13		13		0
Gross Unrealized Gains	4,091		4,091		2,178
Gross Unrealized Losses	154		154		61
Fair Value	49,630		49,630		44,464
U.S. Treasury, government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	13,103		13,103		14,385
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	4,090		4,090		1,151
Gross Unrealized Losses	0		0		305
Fair Value	17,193		17,193		15,231
States and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	607		607		584
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	105		105		68
Gross Unrealized Losses	0		0		3
Fair Value	712		712		649
Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	770		770		460
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	69		69		35
Gross Unrealized Losses	6		6		5
Fair Value	833		833		490
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	144		144		161
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	14		14		12
Gross Unrealized Losses	0		0		0
Fair Value	158		158		173
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	144		144
Fair Value
Without single maturity date	158		158
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,057		2,057		843
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	23		23		3
Gross Unrealized Losses	41		41		2
Fair Value	2,039		2,039		844
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	2,057		2,057
Fair Value
Without single maturity date	2,039		2,039
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	855		855
Allowance for Credit Losses	0		0
Gross Unrealized Gains	24		24
Gross Unrealized Losses	0		0
Fair Value	879		879
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	855		855
Fair Value
Without single maturity date	879		879
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	373		373		498
Allowance for Credit Losses	0		0		0
Gross Unrealized Gains	15		15		18
Gross Unrealized Losses	10		10		5
Fair Value	378		378		$ 511
Amortized Cost
Amortized Cost Basis, without Single Maturity Date	373		373
Fair Value
Without single maturity date	$ 378		$ 378