Investments (Valuation Allowance Rollforward by Portfolio Segment) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	$ 347	$ 481	$ 664
Provision (release)	(13)	(86)	(145)
Charge-offs, net of recoveries	(12)	(37)	(19)
Transfers to held-for-sale	0	(11)	(19)
Ending Balance	322	347	481
Commercial mortgage loans portfolio segment [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	293	398	562
Provision (release)	(35)	(92)	(152)
Charge-offs, net of recoveries	0	(13)	(12)
Transfers to held-for-sale	0	0	0
Ending Balance	258	293	398
Agricultural [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	52	81	88
Provision (release)	4	0	(3)
Charge-offs, net of recoveries	(12)	(24)	(4)
Transfers to held-for-sale	0	(5)	0
Ending Balance	44	52	81
Residential [Member]
Mortgage Loans on Real Estate [Line Items]
Beginning Balance	2	2	14
Provision (release)	18	6	10
Charge-offs, net of recoveries	0	0	(3)
Transfers to held-for-sale	0	(6)	(19)
Ending Balance	$ 20	$ 2	$ 2