Investments (Details 4) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Unrealized gain on:
Pre-tax	$ 1,203		$ 902
Deferred Tax and Amounts Attributable to Noncontrolling Interests	(432)		(324)
Net	771	705	578	605	509	491
Fixed maturities [Member]
Unrealized gain on:
Pre-tax	1,608		1,245
Deferred Tax and Amounts Attributable to Noncontrolling Interests	(573)		(444)
Net	1,035		801
Equity securities [Member]
Unrealized gain on:
Pre-tax	224		184
Deferred Tax and Amounts Attributable to Noncontrolling Interests	(79)		(65)
Net	145		119
Deferred policy acquisition costs [Member]
Unrealized gain on:
Pre-tax	(642)		(537)
Deferred Tax and Amounts Attributable to Noncontrolling Interests	225		188
Net	(417)		(349)
Annuity benefits and other liabilities [Member]
Unrealized gain on:
Pre-tax	13		10
Deferred Tax and Amounts Attributable to Noncontrolling Interests	(5)		(3)
Net	$ 8		$ 7