Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pre- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$ (1,048)	$ 805	$ (1,047)
Less: reclassification adjustment of realized capital gains and losses	265	104	42
Unrealized net capital gains and losses	(1,313)	701	(1,089)
Unrealized foreign currency translation adjustments	(6)	(6)	3
Other comprehensive (loss) income	(1,319)	695	(1,086)
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	366	(282)	367
Less: reclassification adjustment of realized capital gains and losses	(93)	(36)	(15)
Unrealized net capital gains and losses	459	(246)	382
Unrealized foreign currency translation adjustments	2	2	(1)
Other comprehensive (loss) income	461	(244)	381
After- tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(682)	523	(680)
Less: reclassification adjustment of realized capital gains and losses	172	68	27
Unrealized net capital gains and losses	(854)	455	(707)
Unrealized foreign currency translation adjustments	(4)	(4)	2
Other comprehensive (loss) income, after-tax	$ (858)	$ 451	$ (705)