Investments (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Amortized cost
Due in one year or less	$ 2,564
Due after one year through five years	22,645
Due after five years through ten years	17,441
Due after ten years	9,459
Subtotal	52,109
ABS, RMBS and CMBS	6,020
Total amortized cost for fixed income securities	58,129
Fair value
Due in one year or less	2,604
Due after one year through five years	23,399
Due after five years through ten years	18,079
Due after ten years	10,073
Subtotal	54,155
ABS, RMBS and CMBS	6,140
Total fixed income securities	$ 60,295	$ 77,017