Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pre-tax
Unrealized net holding gains arising during the period, net of related offsets, Pre-tax	$ 320	$ 731	$ 1,187	$ 1,068
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	19	111	160	257
Unrealized net capital gains and losses, Pre-tax	301	620	1,027	811
Unrealized foreign currency translation adjustments, Pre-tax	(11)	7	3	22
Unrecognized pension and other postretirement benefit cost, Pre-tax	35	24	66	47
Other comprehensive income, Pre-tax	325	651	1,096	880
Tax
Unrealized net holding gains arising during the period, net of related offsets, Tax	(112)	(256)	(413)	(374)
Less: reclassification adjustment of realized capital gains and losses, Tax	(7)	(39)	(56)	(90)
Unrealized net capital gains and losses, Tax	(105)	(217)	(357)	(284)
Unrealized foreign currency translation adjustments, Tax	4	(3)	(1)	(8)
Unrecognized pension and other postretirement benefit cost, Tax	(11)	(7)	(22)	(15)
Other comprehensive income, Tax	(112)	(227)	(380)	(307)
After-tax
Unrealized net holding gains arising during the period, net of related offsets, After-tax	208	475	774	694
Less: reclassification adjustment of realized capital gains and losses, After-tax	12	72	104	167
Unrealized net capital gains and losses, After-tax	196	403	670	527
Unrealized foreign currency translation adjustments, After-tax	(7)	4	2	14
Unrecognized pension and other postretirement benefit cost, After-tax	24	17	44	32
Other comprehensive income, after-tax	213	424	716	573
Net income (loss)	423	(624)	1,189	(100)
Comprehensive income (loss)	$ 636	$ (200)	$ 1,905	$ 473