Investments - Declines in Fair Value, Fixed Maturities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Debt Securities [Member] | Investment Grade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, One Year or Less, Fair Value	$ 424
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Fair Value	401
Available For Sale Securities, Continuous Unrealized Loss Position, One Year or Less, Amortized Cost	430
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Amortized Cost	411
Available-for-sale Securities, Continuous Unrealized Loss Position, One Year or Less, Aggregate Losses	(6)
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Aggregate Losses	(10)
Debt Securities [Member] | Investment Grade [Member] | One Year Or Less [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	147
Debt Securities [Member] | Investment Grade [Member] | More Than One Year [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	159
Debt Securities [Member] | Below Investment Grade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, One Year or Less, Fair Value	235
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Fair Value	34
Available For Sale Securities, Continuous Unrealized Loss Position, One Year or Less, Amortized Cost	238
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Amortized Cost	37
Available-for-sale Securities, Continuous Unrealized Loss Position, One Year or Less, Aggregate Losses	(3)
Available-for-sale Securities, Continuous Unrealized Loss Position, More Than One Year, Aggregate Losses	(3)
Debt Securities [Member] | Below Investment Grade [Member] | One Year Or Less [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	126
Debt Securities [Member] | Below Investment Grade [Member] | More Than One Year [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	17
Equity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Securities with a fair value significantly lower than cost, excluding hybrid securities	$ 0