Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pre-tax
Unrealized net holding gains arising during the period, net of related offsets	$ 1,180	$ 1,001	$ 1,819
Less: reclassification adjustment of realized capital gains and losses	(84)	579	(349)
Unrealized net capital gains and losses	1,264	422	2,168
Unrealized foreign currency translation adjustments		(2)
Other comprehensive income (loss)	1,264	420	2,168
Tax
Unrealized net holding gains arising during the period, net of related offsets	(414)	(350)	(638)
Less: reclassification adjustment of realized capital gains and losses	29	(203)	122
Unrealized net capital gains and losses	(443)	(147)	(760)
Unrealized foreign currency translation adjustments		1
Other comprehensive income (loss)	(443)	(146)	(760)
After-tax
Unrealized net holding gains arising during the period, net of related offsets	766	651	1,181
Less: reclassification adjustment of realized capital gains and losses	(55)	376	(227)
Unrealized net capital gains and losses	821	275	1,408
Unrealized foreign currency translation adjustments		(1)
Other comprehensive income, after-tax	$ 821	$ 274	$ 1,408