Investments (Details 7) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investments
Net unrealized gains related to changes in valuation of fixed income securities subsequent to impairment measurement date	$ 248	$ 260
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(138)	(183)
Municipal
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(9)	(9)
Asset-backed securities ("ABS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(10)	(10)
Residential mortgage-backed securities ("RMBS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	(114)	(152)
Commercial mortgage-backed securities ("CMBS")
Other-than Impairment Losses Included in Accumulated Other Comprehensive Income
Amount of other-than-temporary impairment losses included in accumulated other comprehensive income for fixed income securities, not included in earnings	$ (5)	$ (12)