Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$ (807)	$ 242	$ (792)	$ 542
Less: reclassification adjustment of realized capital gains and losses	57	(5)	33	(56)
Unrealized net capital gains and losses	(864)	247	(825)	598
Unrealized foreign currency translation adjustments	(2)	5		3
Other comprehensive (loss) income	(866)	252	(825)	601
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	282	(85)	277	(190)
Less: reclassification adjustment of realized capital gains and losses	(20)	2	(12)	20
Unrealized net capital gains and losses	302	(87)	289	(210)
Unrealized foreign currency translation adjustments	1	(2)		(1)
Other comprehensive (loss) income	303	(89)	289	(211)
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(525)	157	(515)	352
Less: reclassification adjustment of realized capital gains and losses	37	(3)	21	(36)
Unrealized net capital gains and losses	(562)	160	(536)	388
Unrealized foreign currency translation adjustments	(1)	3		2
Other comprehensive (loss) income, after-tax	(563)	163	(536)	390
Net income	150	98	259	181
Comprehensive (loss) income	$ (413)	$ 261	$ (277)	$ 571