Investments and Derivative Instruments (Details 4) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Investments and Derivative Instruments [Abstract]
Document Period End Date	Sep. 30, 2012
Available-for-sale Securities, Amortized Cost
One year or less, amortized cost	$ 2,178
Over one year through five years, amortized cost	14,920
Over five years through ten years, amortized cost	15,614
Over ten years, amortized cost	28,287
Subtotal, amortized cost	60,999
Mortgage-backed and asset-backed securities, amortized cost	19,691
Total fixed maturities, AFS, amortized cost	80,690
Available-for-sale Securities, Fair Value
One year or less, fair value	2,195
Over one year through five years, fair value	15,851
Over five years through ten years, fair value	17,161
Over ten years, fair value	31,939
Subtotal, fair value	67,146
Mortgage-backed and asset-backed securities, fair value	19,580
Total fixed maturities, AFS, fair value	$ 86,726	$ 81,809