Investments (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Amortized cost
Due in one year or less	$ 4,556
Due after one year through five years	20,445
Due after five years through ten years	24,033
Due after ten years	16,950
Subtotal	65,984
RMBS and ABS	7,941
Total amortized cost for fixed income securities	73,925
Fair value
Due in one year or less	4,610
Due after one year through five years	21,401
Due after five years through ten years	25,934
Due after ten years	18,357
Subtotal	70,302
RMBS and ABS	7,624
Total fixed income securities	$ 77,926	$ 76,113