8. Investing Activities (Details 1) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investing Activities Details 1
Due in one year or less Amortized Cost	$ 930.5
Due after one year through five years Amortized Cost	2,048.2
Due after five years through ten years Amortized Cost	2,621.4
Due after ten years Amortized Cost	2,498.1
CMBS/RMBS/ABS/CDO/CLO(1) Amortized Cost	3,410.3
Total Amortized Cost	11,508.5
Due in one year or less Fair Value	942.0
Due after one year through five years Fair Value	2,224.5
Due after five years through ten years Fair Value	2,917.6
Due after ten years Fair Value	2,814.2
CMBS/RMBS/ABS/CDO/CLO(1) Fair Value	3,538.4
Available-for-sale debt securities, at fair value	$ 12,436.7	$ 11,797.0