INVESTMENTS - GROSS UNREALIZED LOSSES (Details) $ in Millions	Sep. 30, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Number of fixed maturities in an unrealized loss position greater than 12 months | security	1,461	620
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	$ 21,402	$ 4,315
Less Than 12 Months, Gross Unrealized Losses	732	23
Greater than 12 Months, Fair Value	5,043	4,255
Greater Than 12 Months, Gross Unrealized Losses	611	224
Total, Fair Value	26,445	8,570
Total, Gross Unrealized Losses	1,343	247
Corporate
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	12,410	2,102
Less Than 12 Months, Gross Unrealized Losses	466	17
Greater than 12 Months, Fair Value	2,006	1,163
Greater Than 12 Months, Gross Unrealized Losses	125	39
Total, Fair Value	14,416	3,265
Total, Gross Unrealized Losses	591	56
U.S. Treasury, government and agency
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	8,316	2,150
Less Than 12 Months, Gross Unrealized Losses	251	6
Greater than 12 Months, Fair Value	2,952	3,005
Greater Than 12 Months, Gross Unrealized Losses	477	179
Total, Fair Value	11,268	5,155
Total, Gross Unrealized Losses	728	185
State and Political Sub- divisions
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	19	20
Less Than 12 Months, Gross Unrealized Losses	1	0
Greater than 12 Months, Fair Value	0	0
Greater Than 12 Months, Gross Unrealized Losses	0	0
Total, Fair Value	19	20
Total, Gross Unrealized Losses	1	0
Foreign governments
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	68	11
Less Than 12 Months, Gross Unrealized Losses	2	0
Greater than 12 Months, Fair Value	73	73
Greater Than 12 Months, Gross Unrealized Losses	8	5
Total, Fair Value	141	84
Total, Gross Unrealized Losses	10	5
Residential mortgage-backed
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	13	18
Less Than 12 Months, Gross Unrealized Losses	0	0
Greater than 12 Months, Fair Value	0	0
Greater Than 12 Months, Gross Unrealized Losses	0	0
Total, Fair Value	13	18
Total, Gross Unrealized Losses	0	0
Asset- backed
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	399	7
Less Than 12 Months, Gross Unrealized Losses	6	0
Greater than 12 Months, Fair Value	0	2
Greater Than 12 Months, Gross Unrealized Losses	0	0
Total, Fair Value	399	9
Total, Gross Unrealized Losses	6	0
Redeemable preferred stock
Available For Sale Securities Continuous Unrealized Loss Position [Line Items]
Less Than 12 Months, Fair Value	177	7
Less Than 12 Months, Gross Unrealized Losses	6	0
Greater than 12 Months, Fair Value	12	12
Greater Than 12 Months, Gross Unrealized Losses	1	1
Total, Fair Value	189	19
Total, Gross Unrealized Losses	$ 7	$ 1