Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pre-tax
Unrealized net holding gains arising during the period, net of related offsets, Pre-tax	$ 1,455	$ 2,523	$ 5,015
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	795	(221)	(284)
Unrealized net capital gains and losses, Pre-tax	660	2,744	5,299
Unrealized foreign currency translation adjustments, Pre-tax	(18)	35	63
Unrecognized pension and other postretirement benefit cost, Pre-tax	(371)	142	(292)
Other comprehensive income, Pre-tax	271	2,921	5,070
Tax
Unrealized net holding gains arising during the period, net of related offsets, Tax	(510)	(882)	(1,754)
Less: reclassification adjustment of realized capital gains and losses, Tax	(278)	77	99
Unrealized net capital gains and losses, Tax	(232)	(959)	(1,853)
Unrealized foreign currency translation adjustments, Tax	6	(12)	(22)
Unrecognized pension and other postretirement benefit cost, Tax	132	(48)	78
Other comprehensive income, Tax	(94)	(1,019)	(1,797)
After-tax
Unrealized net holding gains arising during the period, net of related offsets, After-tax	945	1,641	3,261
Less: reclassification adjustment of realized capital gains and losses, After-tax	517	(144)	(185)
Unrealized net capital gains and losses, After-tax	428	1,785	3,446
Unrealized foreign currency translation adjustments, After-tax	(12)	23	41
Unrecognized pension and other postretirement benefit cost, After-tax	(239)	94	(214)
Other comprehensive income, after-tax	$ 177	$ 1,902	$ 3,273