Investments - Fixed Maturities by Maturity Periods (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Amortized Cost:
Due in one year or less	$ 1,151
Due after one year through five years	5,283
Due after five years through ten years	5,260
Due after ten years	2,622
Mortgage and other asset-backed securities	951
Total amortized cost	15,267
Fair Value:
Due in one year or less	1,173
Due after one year through five years	5,656
Due after five years through ten years	5,530
Due after ten years	3,084
Mortgage and other asset-backed securities	1,037
Total fair value	$ 16,480