Fair Value of Assets and Liabilities (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Total commercial mortgage and other loans	$ 36,733,000,000	[1]	$ 35,431,000,000	[1]
Interest income recorded on certain commercial loans	13,000,000		12,000,000		22,000,000
Other Long Term Investments	10,028,000,000	[2]	7,820,000,000	[2]
Notes Of Consolidated Variable Interest Entities	1,577,000,000		524,000,000
Gross Liability Amount [Member]
Embedded Derivative Fair Value of Embedded Derivative	(3,438,000,000)		(3,131,000,000)
Separate Account Assets [Member]
Fair Value Assets Level 1 To Level 2 Transfers Amount	2,900,000,000
Fair Value Assets Level 2 To Level 1 Transfers Amount					3,400,000,000
Commercial Mortgage Loans Fair Value Based On Discounted Cash Flow Pricing Model [Member]
Non-recurring Fair Value net loss adjustment	(2,000,000)		7,000,000		73,000,000
Commercial Mortgage Loans Carrying Value Non Recurring	35,000,000
Cost-method Investments [Member]
Non-recurring Fair Value net loss adjustment	4,000,000		8,000,000		6,000,000
Fair Value Option [Member]
Contractual principal amounts of commercial mortgage loans, for which the fair value option has been elected	156,000,000		598,000,000
Other Long Term Investments	465,000,000		366,000,000
Notes Of Consolidated Variable Interest Entities	1,406,000,000		282,000,000
Commercial Mortgage Loans Carrying Value Non Recurring	162,000,000		603,000,000
Interest Expense	21,000,000
Notes Of Vies Contractual Principle Amount	1,422,000,000		294,000,000
Mortgage Servicing Rights [Member]
Impairment of Intangible	14,000,000		9,000,000		6,000,000
Real Estate [Member]
Non-recurring Fair Value net loss adjustment	4,000,000		22,000,000
Other Intangible Assets [Member]
Impairment of Intangible	$ 46,000,000

[1] Includes loans held at fair value.

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