Investments (Details 7) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Investments
Net unrealized gains related to changes in valuation of fixed income securities subsequent to impairment measurement date	$ 177		$ 164
Other-than-temporary 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)		(117)
Credit Losses on Fixed Income Securities
Beginning balance	(299)	(345)
Additional credit loss for securities previously other-than-temporarily impaired	(1)	(11)
Additional credit loss for securities not previously other-than-temporarily impaired		(15)
Reduction in credit loss for securities disposed or collected	7	28
Ending balance	(293)	(343)
Cumulative credit losses recognized in earnings for securities classified as held for sale	59
Municipal
Other-than-temporary 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)		(5)
ABS
Other-than-temporary 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)
RMBS
Other-than-temporary 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	(87)		(90)
CMBS
Other-than-temporary 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	$ (12)		$ (12)