Investments - Fixed Maturities by Maturity Periods (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Amortized Cost:
Due in one year or less	$ 1,181
Due after one year through five years	5,483
Due after five years through ten years	6,669
Due after ten years	3,134
Mortgage and other asset-backed securities	704
Total amortized cost	17,171
Fair Value:
Due in one year or less	1,201
Due after one year through five years	5,887
Due after five years through ten years	7,020
Due after ten years	3,888
Mortgage and other asset-backed securities	801
Total fair value	$ 18,797