FAIR VALUE DISCLOSURES - FAIR VALUE MEASUREMENT RECONCILIATION FOR ALL LEVELS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	$ (125)	$ 16	$ (20)
Transfers into level 3		25	99
Transfers out of Level 3	(6)	(62)	(125)
Level 3
Total Gains Losses Realized Unrealized Included In [Abstract]
Transfers into level 3	7
Level 3 | Public corporate
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	845	420	380
Net investment income (loss)	5	0	3
Investment gains (losses), net	2	1	2
Subtotal	7	1	5
Other comprehensive income (loss)	4	7	(25)
Purchases	612	572	60
Sales	(331)	(142)	(38)
Transfers into level 3	7	25	99
Transfers out of Level 3	(5)	(38)	(61)
Closing Balance	1,139	845	420
Level 3 | States and political subdivisions
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	42	45	47
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Subtotal	0	0	0
Other comprehensive income (loss)	(1)	(2)	(1)
Purchases	0	0	0
Sales	(1)	(1)	(1)
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	40	42	45
Level 3 | Foreign governments
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	0	1	0
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Subtotal	0	0	0
Other comprehensive income (loss)	0	0	0
Purchases	0	0	1
Sales	0	0	0
Transfers into level 3	0	0	0
Transfers out of Level 3	0	(1)	0
Closing Balance	0	0	1
Level 3 | Commercial mortgage-backed
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	349	503	715
Net investment income (loss)	(2)	0	1
Investment gains (losses), net	(63)	(67)	(38)
Subtotal	(65)	(67)	(37)
Other comprehensive income (loss)	45	14	64
Purchases	0	0	0
Sales	(329)	(87)	(175)
Transfers into level 3	0	0	0
Transfers out of Level 3	0	(14)	(64)
Closing Balance	0	349	503
Level 3 | Residential Mortgage- backed
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	0	0	2
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Subtotal	0	0	0
Other comprehensive income (loss)	0	0	0
Purchases	0	0	0
Sales	0	0	(2)
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	0	0	0
Level 3 | Asset- backed
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	24	40	53
Net investment income (loss)	0	0	0
Investment gains (losses), net	15	0	0
Subtotal	15	0	0
Other comprehensive income (loss)	(9)	1	(4)
Purchases	0	0	0
Sales	(21)	(8)	(9)
Transfers into level 3	0	0	0
Transfers out of Level 3	(1)	(9)	0
Closing Balance	8	24	40
Level 3 | Redeemable preferred stock
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	1	0	0
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Net derivative gains (losses)	0	0	0
Subtotal	0	0	0
Other comprehensive income (loss)	(1)	0	0
Purchases	0	1	0
Sales	0	0	0
Settlements	0	0	0
Activities related to VIEs/VOEs	0	0
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	0	1	0
Level 3 | Other equity investments
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	51	49	61
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	5
Net derivative gains (losses)	0	0	0
Subtotal	0	0	5
Other comprehensive income (loss)	(4)	(2)	2
Purchases	6	0	1
Sales	(3)	0	(20)
Settlements	0	0	0
Activities related to VIEs/VOEs	(22)	60
Transfers into level 3	0	0	0
Transfers out of Level 3	0	(56)	0
Closing Balance	28	51	49
Level 3 | GMIB reinsurance contracts
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	10,314	10,582	10,723
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Net derivative gains (losses)	69	(261)	(316)
Subtotal	69	(261)	(316)
Other comprehensive income (loss)	0	0	0
Purchases	221	223	228
Sales	(116)	(230)	(53)
Settlements	0	0	0
Activities related to VIEs/VOEs	0	0
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	10,488	10,314	10,582
Level 3 | Separate Accounts’ assets
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	313	313	260
Net investment income (loss)	0	0	0
Investment gains (losses), net	29	19	36
Net derivative gains (losses)	0	0	0
Subtotal	29	19	36
Other comprehensive income (loss)	0	0	0
Purchases	13	10	26
Sales	(2)	0	(2)
Settlements	(4)	(7)	(5)
Activities related to VIEs/VOEs	0	0
Transfers into level 3	0	1	0
Transfers out of Level 3	0	(23)	(2)
Closing Balance	349	313	313
Level 3 | GMxB derivative features' liability
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	(5,319)	(5,146)	(4,130)
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Net derivative gains (losses)	1,494	140	(743)
Subtotal	1,494	140	(743)
Other comprehensive income (loss)	0	0	0
Purchases	(344)	(317)	(274)
Sales	5	4	1
Settlements	0	0	0
Activities related to VIEs/VOEs	0	0
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	(4,164)	(5,319)	(5,146)
Level 3 | Contingent payment arrangements
Total Gains Losses Realized Unrealized Included In [Abstract]
Beginning Balance	18	31	42
Net investment income (loss)	0	0	0
Investment gains (losses), net	0	0	0
Net derivative gains (losses)	0	0	0
Subtotal	0	0	0
Other comprehensive income (loss)	0		0
Purchases	0	11	0
Sales	0	0	(11)
Settlements	(7)	(24)	0
Activities related to VIEs/VOEs	0	0
Transfers into level 3	0	0	0
Transfers out of Level 3	0	0	0
Closing Balance	11	18	$ 31
Level 3 Assets And Liabilities Held
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	29	20
Net derivative gains (losses) for assets and liabilities held	1,563	(122)
Other comprehensive income (loss)	40	20
Level 3 Assets And Liabilities Held | Public corporate
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	4	11
Level 3 Assets And Liabilities Held | States and political subdivisions
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	0	(1)
Level 3 Assets And Liabilities Held | Commercial mortgage-backed
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	45	9
Level 3 Assets And Liabilities Held | Asset- backed
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	(9)	1
Level 3 Assets And Liabilities Held | Total debt maturities available for sale
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	40	20
Level 3 Assets And Liabilities Held | GMIB reinsurance contracts
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	69	(262)
Other comprehensive income (loss)	0	0
Level 3 Assets And Liabilities Held | Separate Accounts’ assets
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	29	20
Net derivative gains (losses) for assets and liabilities held	0	0
Other comprehensive income (loss)	0	0
Level 3 Assets And Liabilities Held | GMxB derivative features' liability
Total Gains Losses Realized Unrealized Included In [Abstract]
Investment gains (losses), net	0	0
Net derivative gains (losses) for assets and liabilities held	1,494	140
Other comprehensive income (loss)	$ 0	$ 0