Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 1,578		$ 1,504
Accumulated other comprehensive income, net of tax, end of period	1,578		1,504
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale, before tax, beginning of period	2,335	1,875
Other comprehensive income before reclassification, before tax	135	397
Reclassification adjustment for realized gains, net, included in net income, before tax	(18)	(41)
Effect on other comprehensive income, before tax	117	356
Accumulated unrealized gains, net, on investments available for sale, before tax, end of period	2,452	2,231
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, beginning of period	849	771
Other comprehensive income before reclassification, tax	48	139
Reclassification adjustment for realized gains, net, included in net income, tax	(7)	(15)
Effect on other comprehensive income, tax	41	124
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, end of period	808	647
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, beginning of period	1,527	1,228
Other comprehensive income before reclassification , net of tax	87	258
Reclassification adjustment for realized gains, net, included in net income, net of tax	(11)	(26)
Effect on other comprehensive income, net of tax	76	232
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, end of period	1,603	1,460
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated unrealized losses, net, for pension obligations, before Tax, beginning of period	(18)	(101)
Effect on other comprehensive income, before tax	(1)	2
Accumulated unrealized losses, net, for pension obligations, before Tax, end of period	(19)	(99)
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated unrealized losses, net, for pension obligations, tax, beginning of period	(6)	(35)
Effect on other comprehensive income, tax	0	1
Accumulated unrealized losses, net, for pension obligations, tax, end of period	(6)	(34)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated unrealized losses, net, for pension obligations, net of tax, beginning of period	(12)	(66)
Effect on other comprehensive income, net of tax	(1)	1
Accumulated unrealized losses, net, for pension obligations, net of tax, end of period	(13)	(65)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	3	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Before Tax	(4)	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, beginning of period	(16)	(50)
Effect on other comprehensive income, before tax	(1)	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, end of period	(17)	(50)
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Other comprehensive income before reclassification, tax	1	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, beginning of period	(5)	(17)
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Tax	(1)	0
Effect on other comprehensive income, tax	0	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, end of period	(5)	(17)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other comprehensive income before reclassification , net of tax	2	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, beginning of period, net of tax	(11)	(33)
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Net of Tax	(3)	0
Effect on other comprehensive income, net of tax	(1)	0
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, end of period, net of tax	(12)	(33)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before taxes, beginning of period	2,301	1,724
Change in unrealized gains, net, on investments available for sale, before Tax	117	356
Change in pension obligations, before tax	(1)	2
Change in life deferred acquisition costs, life policy reserves and other, before Tax	(1)	0
Effect on other comprehensive income, before Tax	115	358
Accumulated other comprehensive income, before taxes, end of period	2,416	2,082
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	797	595
Change in unrealized gains, net, on investments available for sale and other invested assets, tax	41	124
Change in pension obligations, tax	0	1
Change in life deferred acquisition costs, life policy reserves and other, tax	0	0
Effect on other comprehensive income, tax	41	125
Accumulated other comprehensive income, tax, end of period	838	720
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	1,578	1,362	1,504	1,129
Change in unrealized gains, net, on investments available for sale, net of tax	76	232
Change in pension obligations, net of tax	(1)	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax	(1)	0
Effect on other comprehensive income, net of tax	74	233
Accumulated other comprehensive income, net of tax, end of period	$ 1,578	$ 1,362	$ 1,504	$ 1,129