Investments (Details 43) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Total Assets	$ 6,896	$ 7,273
Total Liabilities	2,774	3,128
Consolidated Securitization Entities [Member]
Variable Interest Entity [Line Items]
Total Assets	2,949	3,299
Total Liabilities	2,748	3,103
MRSC collateral financing arrangement [Member]
Variable Interest Entity [Line Items]
Total Assets	3,420	3,333
Total Liabilities	0	0
Other limited partnership interests [Member]
Variable Interest Entity [Line Items]
Total Assets	338	360
Total Liabilities	12	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	85	102
Total Liabilities	0	1
Trading Account Assets [Member]
Variable Interest Entity [Line Items]
Total Assets	93	163
Total Liabilities	$ 0	$ 0