Investments (Details 43) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Total Assets	$ 7,111	$ 7,273
Total Liabilities	2,968	3,128
Consolidated Securitization Entities [Member]
Variable Interest Entity [Line Items]
Total Assets	3,131	3,299
Total Liabilities	2,944	3,103
MRSC collateral financing arrangement [Member]
Variable Interest Entity [Line Items]
Total Assets	3,374	3,333
Total Liabilities	0	0
Other limited partnership interests [Member]
Variable Interest Entity [Line Items]
Total Assets	333	360
Total Liabilities	9	6
Real estate joint ventures [Member]
Variable Interest Entity [Line Items]
Total Assets	11	16
Total Liabilities	14	18
Other invested assets [Member]
Variable Interest Entity [Line Items]
Total Assets	102	102
Total Liabilities	1	1
Trading Account Assets [Member]
Variable Interest Entity [Line Items]
Total Assets	160	163
Total Liabilities	$ 0	$ 0