QUARTERLY INTERIM FINANCIAL INFORMATION (UNAUDITED) - REVISION OF PRIOR PERIOD FINANCIAL STATEMENTS - STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Millions	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)	$ 1,712	$ 121	$ 1,615	$ (54)	$ (1,144)	$ 175	$ 600	$ 1,075	$ 1,559	$ 1,679	$ 3,394	$ 706	$ 1,060
Policy charges and fee income		(907)	(847)	(852)					(1,698)	(2,605)	(3,334)	(3,344)	(3,291)
Interest credited to policyholder's account balances		245	205	279					484	729	1,040	1,029	887
Net derivative (gains) losses		406	(1,762)	362					(1,398)	(992)	(890)	1,211	1,161
Changes in:
Deferred policy acquisition costs		(12)	(49)	29					(20)	(32)	268	52	(243)
Future policy benefits				241					1,303	1,208	1,511	431	631
Reinsurance recoverable				(23)					(194)		(416)	(304)	(929)
Current and deferred income taxes				(188)					204		(664)	(742)	50
Other				177					84		189	(161)	(99)
Net cash provided by (used in) operating activities				18					(75)	994	$ 1,077	(461)	(324)
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		66	1,459	(313)	(2,259)	22	1,061	1,720	1,146	1,677		553	1,065
Policy charges and fee income		(914)	(865)	(896)					(1,761)	(2,626)
Interest credited to policyholder's account balances		350	321	337					658	1,008		1,079	973
Net derivative (gains) losses		318	(1,693)	724					(969)	(1,376)		1,163	1,075
Changes in:
Deferred policy acquisition costs		(33)	(82)	125					43	15		287	(254)
Future policy benefits				185					1,381	1,289
Reinsurance recoverable				(44)					(251)
Current and deferred income taxes				(327)					(16)			(826)	49
Other				180					93			(161)	(92)
Net cash provided by (used in) operating activities				18					(75)	994		(461)	(324)
Impact of Revisions
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		55								2		153	(5)
Policy charges and fee income		7								21
Interest credited to policyholder's account balances		(105)								(279)		(50)	(86)
Net derivative (gains) losses		88								384		48	86
Changes in:
Deferred policy acquisition costs		21								(47)		(235)	11
Future policy benefits										(81)
Current and deferred income taxes												84	1
Other												0	(7)
Net cash provided by (used in) operating activities										$ 0		$ 0	$ 0
Restatement, Impact of Revisions
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		55	(59)	50	0	51	7	29	(11)
Policy charges and fee income			(50)	(23)					(72)
Interest credited to policyholder's account balances			(116)	(58)					(174)
Net derivative (gains) losses			197	97					296
Changes in:
Deferred policy acquisition costs			31	(97)					(66)
Future policy benefits				(13)					(13)
Reinsurance recoverable				21					57
Current and deferred income taxes				26					(8)
Other				(3)					(9)
Net cash provided by (used in) operating activities				0					0
As Revised and Adjusted Herein
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		121	1,400	(263)	(2,259)	73	1,068	1,749	1,135
Policy charges and fee income			(915)	(919)					(1,833)
Interest credited to policyholder's account balances			205	279					484
Net derivative (gains) losses			(1,496)	821					(673)
Changes in:
Deferred policy acquisition costs			(51)	28					(23)
Future policy benefits				172					1,368
Reinsurance recoverable				(23)					(194)
Current and deferred income taxes				(301)					(24)
Other				177					84
Net cash provided by (used in) operating activities				18					(75)
Impact of Accounting Change
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)		$ 0	215	209	$ 1,115	$ 102	$ (468)	$ (674)	424
Policy charges and fee income			68	67					135
Interest credited to policyholder's account balances			0	0					0
Net derivative (gains) losses			(266)	(459)					(725)
Changes in:
Deferred policy acquisition costs			$ 2	1					3
Future policy benefits				69					(65)
Reinsurance recoverable				0					0
Current and deferred income taxes				113					228
Other				0					0
Net cash provided by (used in) operating activities				$ 0					$ 0