SIGNIFICANT ACCOUNTING POLICIES - ASSUMPTION UPDATES (Details) - USD ($) $ in Millions	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Accounting Estimate [Line Items]
Amortization of deferred policy acquisition cost, net	$ 33	$ 76	$ (126)	$ (55)	$ 22	$ (172)	$ (50)	$ (9)	$ (15)	$ (64)	$ (368)	$ 257	$ 345
Policy charges and fee income	914	856	858	854	819	795	1,712	1,614	2,626	2,468	3,342	3,284	3,156
Policyholders’ benefits	995	1,348	981	616	1,087	1,087	2,345	2,174	3,308	2,790	2,746	2,455	3,707
Amortization of deferred cost of reinsurance assets									(111)	(115)
Net income (loss)	$ 66	$ 1,714	$ (120)	$ 137	$ 576	$ 1,067	$ 1,593	$ 1,642	1,677	1,779	$ 524	$ 1,070	$ 3,100
Variable and Interest Sensitive Life
Change in Accounting Estimate [Line Items]
Net income (loss)										(14)
Long-term lapse and partial withdrawal behavior
Change in Accounting Estimate [Line Items]
Amortization of deferred policy acquisition cost, net									32
Policyholders’ benefits									602
Increase (decrease) in the fair value of the reinsurance contract asset									1,532
Amortization of deferred cost of reinsurance assets									226
Net income (loss)									$ 772
Mortality Assumption | Variable and Interest Sensitive Life
Change in Accounting Estimate [Line Items]
Amortization of deferred policy acquisition cost, net										70
Policy charges and fee income										(16)
General Account Spread Assumption | Variable and Interest Sensitive Life
Change in Accounting Estimate [Line Items]
Amortization of deferred policy acquisition cost, net										(79)
Policy charges and fee income										$ 4