Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pre- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$ 134	$ (1,048)	$ 805
Less: reclassification adjustment of realized capital gains and losses	(100)	265	104
Unrealized net capital gains and losses	234	(1,313)	701
Unrealized foreign currency translation adjustments	6	(6)	(6)
Other comprehensive income (loss)	240	(1,319)	695
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(46)	366	(282)
Less: reclassification adjustment of realized capital gains and losses	35	(93)	(36)
Unrealized net capital gains and losses	(81)	459	(246)
Unrealized foreign currency translation adjustments	(2)	2	2
Other comprehensive income (loss)	(83)	461	(244)
After- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	88	(682)	523
Less: reclassification adjustment of realized capital gains and losses	(65)	172	68
Unrealized net capital gains and losses	153	(854)	455
Unrealized foreign currency translation adjustments	4	(4)	(4)
Other comprehensive income (loss), after-tax	$ 157	$ (858)	$ 451