Investments (Details 32) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Allowance for Loan and Lease Losses, Provision for Loss, Net
Beginning Balance	$ 566	$ 734	$ 664	$ 721
Provision/(release)	(36)	(23)	(130)	11
Charge-offs, net of recoveries	(1)	(45)	(5)	(66)
Ending Balance	529	666	529	666
Commercial mortgage loans portfolio segment [Member]
Allowance for Loan and Lease Losses, Provision for Loss, Net
Beginning Balance	469	621	562	589
Provision/(release)	(41)	(27)	(134)	6
Charge-offs, net of recoveries	0	(21)	0	(22)
Ending Balance	428	573	428	573
Agricultural mortgage loans portfolio segment [Member]
Allowance for Loan and Lease Losses, Provision for Loss, Net
Beginning Balance	79	96	88	115
Provision/(release)	3	1	(3)	0
Charge-offs, net of recoveries	0	(21)	(3)	(39)
Ending Balance	82	76	82	76
Residential mortgage loans portfolio segment [Member]
Allowance for Loan and Lease Losses, Provision for Loss, Net
Beginning Balance	18	17	14	17
Provision/(release)	2	3	7	5
Charge-offs, net of recoveries	(1)	(3)	(2)	(5)
Ending Balance	$ 19	$ 17	$ 19	$ 17