Fair Value of Assets and Liabilities (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Total commercial mortgage and other loans	$ 46,432,000,000	[1],[2]	$ 41,008,000,000	[1],[2]
Other Long Term Investments	10,921,000,000	[2]	10,328,000,000	[2]
Notes Of Consolidated Variable Interest Entities	6,058,000,000	[2]	3,302,000,000	[2]
Embedded Derivative Fair Value of Embedded Derivative	8,162,000,000		430,000,000
Fair Value Assets Level1 To Level2 Transfers	2,100,000,000		4,000,000,000
Fair Value Assets Level2 to Level1 Transfers	100,000,000		5,000,000,000
DerivativeAssetCollateralObligationToReturnCashOffset	(12,332,000,000)	[3]	(7,241,000,000)	[3]
Derivative Liability Collateral Right To Reclaim Cash Offset	(6,661,000,000)	[3]	(7,257,000,000)	[3]
Netting And Collateral [Member]
Embedded Derivative Fair Value of Embedded Derivative	(5,671,000,000)		16,000,000
Commercial Mortgage Loans Fair Value Based On Discounted Cash Flow Pricing Model [Member]
Non-recurring Fair Value net loss adjustment	0		9,000,000		(2,000,000)
Commercial Mortgage Loans Carrying Value Non Recurring	0		27,000,000
Cost-method Investments [Member]
Non-recurring Fair Value net loss adjustment	21,000,000		21,000,000		4,000,000
Non Accrual Loans [Member]
Contractual principal amounts of commercial mortgage loans, for which the fair value option has been elected	0
Commercial Mortgage Loans Carrying Value Non Recurring	0
Fair Value Option [Member]
Interest income recorded on certain commercial loans	11,000,000		10,000,000		13,000,000
Contractual principal amounts of commercial mortgage loans, for which the fair value option has been elected	372,000,000		154,000,000
Other Long Term Investments	1,082,000,000		873,000,000
Notes Of Consolidated Variable Interest Entities	6,033,000,000		3,254,000,000
Commercial Mortgage Loans Carrying Value Non Recurring	380,000,000		158,000,000
Interest Expense	200,000,000		106,000,000
Notes Of Vies Contractual Principle Amount	6,216,000,000		3,276,000,000
Mortgage Servicing Rights [Member]
Non-recurring Fair Value net loss adjustment	(7,000,000)		(16,000,000)		14,000,000
Real Estate [Member]
Non-recurring Fair Value net loss adjustment	0		0		4,000,000
Other Intangible Assets [Member]
Non-recurring Fair Value net loss adjustment	0		0		46,000,000
Liability For Future Policy Benefits [Member]
Embedded Derivative Fair Value of Embedded Derivative	(8,200,000,000)		(400,000,000)
Embedded Derivative Fair Value Of Embedded Derivative Liability	8,800,000,000		1,900,000,000
Embedded Derivative Fair Value Of Embedded Derivative Asset	$ 600,000,000		$ 1,500,000,000

[1] Includes loans held at fair value.

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

[3] “Netting” amounts represent cash collateral and the impact of offsetting asset and liability positions held with the same counterparty.