Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 1,280		$ 1,280			$ 1,744
Accumulated other comprehensive income, net of tax, end of period	1,280		1,280
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	2,357	$ 2,687	2,719	$ 2,335
Other comprehensive income before reclassification, before tax	(363)	(55)	(620)	332
Reclassification adjustment, before tax	(2)	(65)	(107)	(100)
Effect on other comprehensive income, before tax	(365)	(120)	(727)	232
Accumulated other comprehensive income, before tax, end of period	1,992	2,567	1,992	2,567
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	815	931	942	808
Other comprehensive income before reclassification, tax	(126)	(20)	(216)	115
Reclassification adjustment, tax	(1)	(22)	(38)	(34)
Effect on other comprehensive income, tax	(127)	(42)	(254)	81
Accumulated other comprehensive income, tax, end of period	688	889	688	889
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	1,304	1,678	1,304	1,678	$ 1,542	1,777	$ 1,756	$ 1,527
Other comprehensive income before reclassification, net of tax	(237)	(35)	(404)	217
Reclassification adjustment, net of tax	(1)	(43)	(69)	(66)
Effect on other comprehensive income, net of tax	(238)	(78)	(473)	151
Accumulated other comprehensive income, net of tax, end of period	1,304	1,678	1,304	1,678
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(33)	(19)	(36)	(18)
Other comprehensive income before reclassification, before tax	0	0	0	0
Reclassification adjustment, before tax	1	0	4	0
Effect on other comprehensive income, before tax	1	1	4	0
Accumulated other comprehensive income, before tax, end of period	(32)	(18)	(32)	(18)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(11)	(6)	(12)	(6)
Other comprehensive income before reclassification, tax	0	0	0	0
Reclassification adjustment, tax	0	0	1	0
Effect on other comprehensive income, tax	0	0	1	0
Accumulated other comprehensive income, tax, end of period	(11)	(6)	(11)	(6)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(21)	(12)	(21)	(12)	(22)	(24)	(13)	(12)
Other comprehensive income before reclassification, net of tax	0	0	0	0
Reclassification adjustment, net of tax	1	0	3	0
Effect on other comprehensive income, net of tax	1	1	3	0
Accumulated other comprehensive income, net of tax, end of period	(21)	(12)	(21)	(12)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(8)	(16)	(12)	(16)
Other comprehensive income before reclassification, before tax	5	5	11	6
Reclassification adjustment, before tax	(1)	0	(3)	(1)
Effect on other comprehensive income, before tax	4	5	8	5
Accumulated other comprehensive income, before tax, end of period	(4)	(11)	(4)	(11)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(2)	(5)	(3)	(5)
Other comprehensive income before reclassification, tax	1	2	3	3
Reclassification adjustment, tax	0	0	(1)	(1)
Effect on other comprehensive income, tax	1	2	2	2
Accumulated other comprehensive income, tax, end of period	(1)	(3)	(1)	(3)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(3)	(8)	(3)	(8)	(6)	(9)	(11)	(11)
Other comprehensive income before reclassification, net of tax	4	3	8	3
Reclassification adjustment, net of tax	(1)	0	(2)	0
Effect on other comprehensive income, net of tax	3	3	6	3
Accumulated other comprehensive income, net of tax, end of period	(3)	(8)	(3)	(8)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	2,316	2,652	2,671	2,301
Change in unrealized gains, net, on investments available for sale, before tax	(365)	(120)	(727)	232
Change in pension obligations, before tax	1	1	4	0
Change in life deferred acquisition costs, life policy reserves and other, before tax	4	5	8	5
Effect on other comprehensive income, before tax	(360)	(114)	(715)	237
Accumulated other comprehensive income, before tax, end of period	1,956	2,538	1,956	2,538
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	802	920	927	797
Change in unrealized gains, net, on investments available for sale, tax	(127)	(42)	(254)	81
Change in pension obligations, tax	0	0	1	0
Change in life deferred acquisition costs, life policy reserves and other, tax	1	2	2	2
Effect on other comprehensive income, tax	(126)	(40)	(251)	83
Accumulated other comprehensive income, tax, end of period	676	880	676	880
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	1,280	1,658	1,280	1,658	$ 1,514	$ 1,744	$ 1,732	$ 1,504
Change in unrealized gains, net, on investments available for sale, net of tax	(238)	(78)	(473)	151
Change in pension obligations, net of tax	1	1	3	0
Change in life deferred acquisition costs, life policy reserves and other, net of tax	3	3	6	3
Effect on other comprehensive income, net of tax	(234)	(74)	(464)	154
Accumulated other comprehensive income, net of tax, end of period	$ 1,280	$ 1,658	$ 1,280	$ 1,658