Investments (Commercial Mortgage and Other Loans) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Total net commercial and agricultural mortgage loans by property type	$ 33,873		$ 31,952
Valuation allowance	(42)		(54)
Total net other loans	2,949		3,479
Total commercial mortgage and other loans	36,822	[1],[2]	35,431	[1],[2]
Office buildings [Member]
Commercial mortgage loans	6,655		6,391
Retail stores [Member]
Commercial mortgage loans	8,182		7,309
Apartment Complexes [Member]
Commercial mortgage loans	5,312		5,277
Industrial Buildings [Member]
Commercial mortgage loans	7,493		7,049
Agricultural Properties [Member]
Commercial mortgage loans	2,169		2,046
Hospitality [Member]
Commercial mortgage loans	1,509		1,486
Other Commercial Loans [Member]
Commercial mortgage loans	2,827		2,707
Commercial Mortgage Loan [Member]
Commercial mortgage loans	31,978		30,219
Commercial Mortgage Loan [Member] | Agricultural Properties [Member]
Commercial mortgage loans	34,147		32,265
Valuation allowance	(274)		(313)
Uncollateralized Loans [Member]
Total other loans	1,939		2,323
Residential Property Loan [Member]
Total other loans	901		1,034
Other Collateralized Loans [Member]
Total other loans	151		176
Total Other Loans [Member]
Total other loans	$ 2,991		$ 3,533

[1]          (1) See Note 5 for details of balances associated with variable interest entities.

[2] Includes loans held at fair value.