Investments (Unconsolidated Variable Interest Entities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Total Assets	$ 10,904	$ 12,477
Total Liabilities	11,382	13,002
Other limited partnership interests [Member]
Variable Interest Entity [Line Items]
Total Assets	1,573	1,408
Total Liabilities	2,047	1,930
Real estate joint ventures [Member]
Variable Interest Entity [Line Items]
Total Assets	68	71
Total Liabilities	72	74
Structured securities (RMBS, CMBS and ABS) [Member]
Variable Interest Entity [Line Items]
Total Assets	8,715	10,347
Total Liabilities	8,715	10,347
US and foreign corporate securities [Member]
Variable Interest Entity [Line Items]
Total Assets	548	651
Total Liabilities	$ 548	$ 651