Deferred Policy Acquisition Costs and Value of Business Acquired (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	$ 385	$ 476
Deferrals of commissions and expenses	15	21
Amortization:
Amortization, excluding unlocking	(18)	(17)
Unlocking (1)	(29)	1
Interest accrued	9	9
Net amortization included in the Condensed Consolidated Statements of Operations	(38)	(7)
Change due to unrealized capital gains/losses on available-for-sale securities	85	(14)
Ending balance	447	476
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance	367	537
Deferrals of commissions and expenses	2	1
Amortization, excluding unlocking	(20)	(20)
Unlocking (1)	(17)	13
Interest accrued	10	12
Net amortization included in the Condensed Consolidated Statements of Operations	(27)	5
Change due to unrealized capital gains/losses on available-for-sale securities	108	(19)
Ending balance	450	524
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance	752	1,013
Deferrals of commissions and expenses	17	22
Amortization, excluding unlocking	(38)	(37)
Unlocking (1)	(46)	14
Interest accrued	19	21
Net amortization included in the Condensed Consolidated Statements of Operations	(65)	(2)
Change due to unrealized capital gains/losses on available-for-sale securities	193	(33)
Ending balance	$ 897	$ 1,000
Minimum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Value of Business Acquired (VOBA), Interest accrued percentage	5.50%	5.50%
Maximum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Value of Business Acquired (VOBA), Interest accrued percentage	7.00%	7.00%
Guaranteed minimum interest rates
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Unlocking (1)	$ (43)