Investments (Valuation Allowance Rollforward by Portfolio Segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	$ 326	$ 332	$ 322	$ 347
Provision (release)	(8)	(24)	(3)	(35)
Charge-offs, net of recoveries	(24)	(6)	(25)	(10)
Ending Balance	294	302	294	302
Commercial mortgage loans portfolio segment [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	259	275	258	293
Provision (release)	(5)	(33)	(4)	(51)
Charge-offs, net of recoveries	(24)	0	(24)	0
Ending Balance	230	242	230	242
Agricultural [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	42	54	44	52
Provision (release)	0	1	(2)	7
Charge-offs, net of recoveries	0	(6)	0	(10)
Ending Balance	42	49	42	49
Residential [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	25	3	20	2
Provision (release)	(3)	8	3	9
Charge-offs, net of recoveries	0	0	(1)	0
Ending Balance	$ 22	$ 11	$ 22	$ 11