Investments and Derivative Instruments (Details 11) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Variable Interest [Line Items]
Total Liabilities	$ 439	$ 394
CDOs [Member]
Variable Interest [Line Items]
Total Assets	510	729
Total Liabilities	439	393
Maximum Exposure to Loss	48	289
Limited partnerships [Member] | Consolidated VIEs [Member]
Variable Interest [Line Items]
Total Assets	7	14
Total Liabilities	0	1
Maximum Exposure to Loss	7	13
Consolidated VIEs [Member]
Variable Interest [Line Items]
Total Assets	517	743
Total Liabilities	439	394
Maximum Exposure to Loss	$ 55	$ 302