REVISION OF PRIOR PERIOD FINANCIAL STATEMENTS - CASH FLOW DISCLOSURES (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Cash flow from operating activities:
Net income (loss)	$ (1,958)	$ (133)	$ 121	$ 1,613	$ (54)	$ (2,091)	$ 1,559	$ 1,679
Policy charges and fee income	(904)		(907)	(846)	(852)	(1,773)	(1,698)	(2,605)
Interest credited to policyholders’ account balances	240	255	197	208	239	495	448	681	$ 921	$ 905
Net derivative (gains) losses	$ 312	860	454	(1,763)	402	1,172	(1,362)	(944)	(771)	1,335
Changes in:
Deferred policy acquisition costs		58			29	89	(20)	(32)
Future policy benefits					241	396	1,303	1,208
Reinsurance recoverable					(23)	15	(194)
Current and deferred income taxes		(77)			(188)	(645)	204
Other, net		(52)			151	416	84
Net cash provided by (used in) operating activities		(21)			18	$ 1,190	(75)	994	1,077	(461)
As Previously Reported
Cash flow from operating activities:
Net income (loss)		(40)	66	1,459	(313)		1,146	1,677
Policy charges and fee income			(914)	(865)	(896)		(1,761)	(2,626)
Interest credited to policyholders’ account balances		338	350	321	337		658	1,008	1,040	1,029
Net derivative (gains) losses		777	318	(1,693)	724		(969)	(1,376)	(890)	1,211
Changes in:
Deferred policy acquisition costs		10			125		43	15
Future policy benefits					185		1,381	1,289
Reinsurance recoverable					(44)		(251)
Current and deferred income taxes		(52)			(327)		(16)
Other, net		(122)			154		93
Net cash provided by (used in) operating activities		(21)			18		(75)	994	1,077	(461)
Impact of Revisions
Cash flow from operating activities:
Net income (loss)		(93)	55	(61)	50		(11)	2
Policy charges and fee income			7	(49)	(23)		(72)	21
Interest credited to policyholders’ account balances		(83)	(153)	(113)	(98)		(210)	(327)	(119)	(124)
Net derivative (gains) losses		83	$ 136	196	137		332	432	119	124
Changes in:
Deferred policy acquisition costs		48			(97)		(66)	(47)
Future policy benefits					(13)		(13)	(81)
Reinsurance recoverable					21		57
Current and deferred income taxes		(25)			26		(8)
Other, net		70			(3)		(9)
Net cash provided by (used in) operating activities		$ 0			0		0	$ 0	$ 0	$ 0
As Revised and Adjusted Herein
Cash flow from operating activities:
Net income (loss)				1,398	(263)		1,135
Policy charges and fee income				(914)	(919)		(1,833)
Interest credited to policyholders’ account balances				208	239		448
Net derivative (gains) losses				(1,497)	861		(637)
Changes in:
Deferred policy acquisition costs					28		(23)
Future policy benefits					172		1,368
Reinsurance recoverable					(23)		(194)
Current and deferred income taxes					(301)		(24)
Other, net					151		84
Net cash provided by (used in) operating activities					18		(75)
Impact of Accounting Change
Cash flow from operating activities:
Net income (loss)				215	209		424
Policy charges and fee income				68	67		135
Interest credited to policyholders’ account balances				0	0		0
Net derivative (gains) losses				$ (266)	(459)		(725)
Changes in:
Deferred policy acquisition costs					1		3
Future policy benefits					69		(65)
Reinsurance recoverable					0		0
Current and deferred income taxes					113		228
Other, net					0		0
Net cash provided by (used in) operating activities					$ 0		$ 0