Investments (Details 4) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Unrealized gain on:
Pre-tax	$ 1,102	$ 902
Deferred Tax Amounts Attributable to Noncontrolling Interests	(397)	(324)
Net	705	578	509	491
Fixed maturity securities [Member]
Unrealized gain on:
Pre-tax	1,377	1,245
Deferred Tax Amounts Attributable to Noncontrolling Interests	(492)	(444)
Net	885	801
Equity Securities [Member]
Unrealized gain on:
Pre-tax	254	184
Deferred Tax Amounts Attributable to Noncontrolling Interests	(90)	(65)
Net	164	119
Deferred Policy Acquisition Costs [Member]
Unrealized gain on:
Pre-tax	(539)	(537)
Deferred Tax Amounts Attributable to Noncontrolling Interests	189	188
Net	(350)	(349)
Annuity Benefits And Other Liabilities [Member]
Unrealized gain on:
Pre-tax	10	10
Deferred Tax Amounts Attributable to Noncontrolling Interests	(4)	(3)
Net	$ 6	$ 7