Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pre-tax
Unrealized net holding gains arising during the period, net of related offsets, Pre-tax	$ 866	$ 344
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	140	153
Unrealized net capital gains and losses, Pre-tax	726	191
Unrealized foreign currency translation adjustments, Pre-tax	14	15
Unrecognized pension and other postretirement benefit cost, Pre-tax	31	23
Other comprehensive income, Pre-tax	771	229
Tax
Unrealized net holding gains arising during the period, net of related offsets, Tax	(301)	(121)
Less: reclassification adjustment of realized capital gains and losses, Tax	(49)	(54)
Unrealized net capital gains and losses, Tax	(252)	(67)
Unrealized foreign currency translation adjustments, Tax	(5)	(5)
Unrecognized pension and other postretirement benefit cost, Tax	(11)	(8)
Other comprehensive income, Tax	(268)	(80)
After-tax
Unrealized net holding gains arising during the period, net of related offsets, After-tax	565	223
Less: reclassification adjustment of realized capital gains and losses, After-tax	91	99
Unrealized net capital gains and losses, After-tax	474	124
Unrealized foreign currency translation adjustments, After-tax	9	10
Unrecognized pension and other postretirement benefit cost, After-tax	20	15
Other comprehensive income, after-tax	503	149
Net income	766	524
Comprehensive income	$ 1,269	$ 673