Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets, Pre-tax	$ 68	$ 1,177	$ (1,285)	$ 2,337
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	(28)	(70)	438	63
Unrealized net capital gains and losses, Pre-tax	96	1,247	(1,723)	2,274
Unrecognized pension and other postretirement benefit cost arising during the period, Pre-tax	934	(13)	943	(33)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Pre-tax	(117)	(43)	(247)	(129)
Unrecognized pension and other postretirement benefit cost, Pre-tax	1,051	30	1,190	96
Unrealized foreign currency translation adjustments, Pre-tax	20	19	(31)	22
Other comprehensive (loss) income, Pre-tax	1,167	1,296	(564)	2,392
Tax
Unrealized net holding gains arising during the period, net of related offsets, Tax	(23)	(412)	450	(816)
Less: reclassification adjustment of realized capital gains and losses, Tax	10	25	(153)	(22)
Unrealized net capital gains and losses, Tax	(33)	(437)	603	(794)
Unrecognized pension and other postretirement benefit cost arising during the period, Tax	(327)	5	(329)	13
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Tax	40	15	86	45
Unrecognized pension and other postretirement benefit cost, Tax	(367)	(10)	(415)	(32)
Unrealized foreign currency translation adjustments, Tax	(7)	(7)	11	(8)
Other comprehensive (loss) income, Tax	(407)	(454)	199	(834)
After-tax
Unrealized net holding gains arising during the period, net of related offsets, After-tax	45	765	(835)	1,521
Less: reclassification adjustment of realized capital gains and losses, After-tax	(18)	(45)	285	41
Unrealized net capital gains and losses, After-tax	63	810	(1,120)	1,480
Unrecognized pension and other postretirement benefit cost arising during the period, After-tax	607	(8)	614	(20)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, After-tax	(77)	(28)	(161)	(84)
Unrecognized pension and other postretirement benefit cost, After-tax	684	20	775	64
Unrealized foreign currency translation adjustments, After-tax	13	12	(20)	14
Other comprehensive income (loss), after-tax	760	842	(365)	1,558
Net income	316	723	1,459	1,912
Comprehensive income	$ 1,076	$ 1,565	$ 1,094	$ 3,470