Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$ (1,003)	$ 322	$ (528)	$ 1,039
Less: reclassification adjustment of realized capital gains and losses	100	232	251	265
Unrealized net capital gains and losses	(1,103)	90	(779)	774
Unrealized foreign currency translation adjustments	(13)	20	(55)	(5)
Unrecognized pension and other postretirement benefit cost arising during the period	(3)	(4)	8	0
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(33)	(15)	(65)	(28)
Unrecognized pension and other postretirement benefit cost	30	11	73	28
Other comprehensive (loss) income	(1,086)	121	(761)	797
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	350	(112)	184	(363)
Less: reclassification adjustment of realized capital gains and losses	(35)	(81)	(88)	(93)
Unrealized net capital gains and losses	385	(31)	272	(270)
Unrealized foreign currency translation adjustments	4	(7)	19	2
Unrecognized pension and other postretirement benefit cost arising during the period	2	2	(1)	1
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	12	5	23	10
Unrecognized pension and other postretirement benefit cost	(10)	(3)	(24)	(9)
Other comprehensive income (loss), Tax	379	(41)	267	(277)
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(653)	210	(344)	676
Less: reclassification adjustment of realized capital gains and losses	65	151	163	172
Unrealized net capital gains and losses	(718)	59	(507)	504
Unrealized foreign currency translation adjustments	(9)	13	(36)	(3)
Unrecognized pension and other postretirement benefit cost arising during the period	(1)	(2)	7	1
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(21)	(10)	(42)	(18)
Unrecognized pension and other postretirement benefit cost	20	8	49	19
Other comprehensive (loss) income, after-tax	$ (707)	$ 80	$ (494)	$ 520