Investments (Details 39) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Mortgage loans, net [Member]
Information about purchased credit impaired investments as of their respective acquisition dates
Contractually required payments receivable (including interest)	$ 0	$ 0
Cash flows expected to be collected	0	0
Fair value of investments acquired	0	0
Fixed maturity securities [Member]
Information about purchased credit impaired investments as of their respective acquisition dates
Contractually required payments receivable (including interest)	4,651	1,083
Cash flows expected to be collected	2,724	1,021
Fair value of investments acquired	$ 1,503	$ 633