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
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$ (813)	$ (203)	$ (1,306)	$ 777
Less: reclassification adjustment of realized capital gains and losses	18	293	304	499
Unrealized net capital gains and losses	(831)	(496)	(1,610)	278
Unrealized foreign currency translation adjustments	(22)	(26)	(77)	(31)
Unrecognized pension and other postretirement benefit cost arising during the period	7	4	15	4
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(31)	(14)	(96)	(42)
Unrecognized pension and other postretirement benefit cost	38	18	111	46
Other comprehensive loss	(815)	(504)	(1,576)	293
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	285	70	457	(272)
Less: reclassification adjustment of realized capital gains and losses	(6)	(103)	(106)	(175)
Unrealized net capital gains and losses	291	173	563	(97)
Unrealized foreign currency translation adjustments	8	9	27	11
Unrecognized pension and other postretirement benefit cost arising during the period	(2)	(2)	(3)	(1)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	11	4	34	14
Unrecognized pension and other postretirement benefit cost	(13)	(6)	(37)	(15)
Other comprehensive income (loss), Tax	286	176	553	(101)
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(528)	(133)	(849)	505
Less: reclassification adjustment of realized capital gains and losses	12	190	198	324
Unrealized net capital gains and losses	(540)	(323)	(1,047)	181
Unrealized foreign currency translation adjustments	(14)	(17)	(50)	(20)
Unrecognized pension and other postretirement benefit cost arising during the period	5	2	12	3
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(20)	(10)	(62)	(28)
Unrecognized pension and other postretirement benefit cost	25	12	74	31
Other comprehensive (loss) income, after-tax	$ (529)	$ (328)	$ (1,023)	$ 192