INVESTMENTS - AVAILABLE FOR SALE SECURITIES (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 40,638
Fair Value	40,394	$ 36,358
Amortized Cost		34,988
Gross Unrealized Gains		1,774
Gross Unrealized Losses		247
Fair Value		36,515
OTTI in AOCI		2
Amortized Cost
Due in one year or less	1,683
Due in years two through five	7,582
Due in years six through ten	12,810
Due after ten years	17,262
Subtotal	39,337
Fair Value
Due in one year or less	1,688
Due in years two through five	7,664
Due in years six through ten	12,641
Due after ten years	17,065
Subtotal	39,058
Total	40,394
Public corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,368
Gross Unrealized Gains	356
Gross Unrealized Losses	423
Fair Value	17,301
Amortized Cost		13,645
Gross Unrealized Gains		725
Gross Unrealized Losses		25
Fair Value		14,345
OTTI in AOCI	0	0
Private corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,004
Gross Unrealized Gains	88
Gross Unrealized Losses	147
Fair Value	6,945
Amortized Cost		6,951
Gross Unrealized Gains		217
Gross Unrealized Losses		31
Fair Value		7,137
OTTI in AOCI	0	0
U.S. Treasury, government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14,112
Gross Unrealized Gains	206
Gross Unrealized Losses	415
Fair Value	13,903
Amortized Cost		12,644
Gross Unrealized Gains		676
Gross Unrealized Losses		185
Fair Value		13,135
OTTI in AOCI	0	0
State and Political Sub- divisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	413
Gross Unrealized Gains	50
Gross Unrealized Losses	1
Fair Value	462
Amortized Cost		414
Gross Unrealized Gains		67
Gross Unrealized Losses		0
Fair Value		481
OTTI in AOCI	0	0
Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	440
Gross Unrealized Gains	18
Gross Unrealized Losses	11
Fair Value	447
Amortized Cost		387
Gross Unrealized Gains		27
Gross Unrealized Losses		5
Fair Value		409
OTTI in AOCI	0	0
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	211
Gross Unrealized Gains	10
Gross Unrealized Losses	0
Fair Value	221
Amortized Cost		236
Gross Unrealized Gains		15
Gross Unrealized Losses		0
Fair Value		251
OTTI in AOCI	0	0
Amortized Cost
Without single maturity date	211
Fair Value
Without single maturity date	221
Asset- backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	621
Gross Unrealized Gains	1
Gross Unrealized Losses	5
Fair Value	617
Amortized Cost		93
Gross Unrealized Gains		3
Gross Unrealized Losses		0
Fair Value		96
OTTI in AOCI	2	2
Amortized Cost
Without single maturity date	621
Fair Value
Without single maturity date	617
Redeemable preferred stock
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	469
Gross Unrealized Gains	33
Gross Unrealized Losses	4
Fair Value	498
Amortized Cost		461
Gross Unrealized Gains		44
Gross Unrealized Losses		1
Fair Value		504
OTTI in AOCI	0	0
Amortized Cost
Without single maturity date	469
Fair Value
Without single maturity date	498
Total Fixed Maturities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	40,638	34,831
Gross Unrealized Gains	762
Gross Unrealized Losses	1,006
Fair Value	40,394
Amortized Cost	40,638	34,831
Gross Unrealized Gains		1,774
Gross Unrealized Losses		247
Fair Value		36,358
OTTI in AOCI	$ 2	2
Equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		157
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		157
OTTI in AOCI		$ 0