Investments - Fixed Maturities by Maturity Periods (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Amortized Cost:
Due in one year or less	$ 1,161
Due after one year through five years	5,530
Due after five years through ten years	6,285
Due after ten years	2,785
Mortgage and other asset-backed securities	837
Total amortized cost	16,598
Fair Value:
Due in one year or less	1,180
Due after one year through five years	5,962
Due after five years through ten years	6,701
Due after ten years	3,535
Mortgage and other asset-backed securities	943
Total fair value	$ 18,321