Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pre-tax
Unrealized net holding gains arising during the period, net of related offsets	$ 21	$ 300
Less: reclassification adjustment of realized capital gains and losses	(18)	(51)
Unrealized net capital gains and losses	39	351
Unrealized foreign currency translation adjustments	2	(2)
Other comprehensive income (loss)	41	349
Tax
Unrealized net holding gains arising during the period, net of related offsets	(7)	(105)
Less: reclassification adjustment of realized capital gains and losses	6	18
Unrealized net capital gains and losses	(13)	(123)
Unrealized foreign currency translation adjustments	(1)	1
Other comprehensive income (loss)	(14)	(122)
After-tax
Unrealized net holding gains arising during the period, net of related offsets	14	195
Less: reclassification adjustment of realized capital gains and losses	(12)	(33)
Unrealized net capital gains and losses	26	228
Unrealized foreign currency translation adjustments	1	(1)
Other comprehensive income, after-tax	27	227
Net income	109	83
Comprehensive income	$ 136	$ 310