Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets, Pre-tax	$ (1,559)	$ 320	$ (1,361)	$ 1,187
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	369	19	458	160
Unrealized net capital gains and losses, Pre-tax	(1,928)	301	(1,819)	1,027
Unrecognized pension and other postretirement benefit cost arising during the period, Pre-tax	7	(8)	9	(20)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Pre-tax	(64)	(43)	(130)	(86)
Unrecognized pension and other postretirement benefit cost, Pre-tax	71	35	139	66
Unrealized foreign currency translation adjustments, Pre-tax	(33)	(11)	(51)	3
Other comprehensive (loss) income, Pre-tax	(1,890)	325	(1,731)	1,096
Tax
Unrealized net holding gains arising during the period, net of related offsets, Tax	545	(112)	476	(413)
Less: reclassification adjustment of realized capital gains and losses, Tax	(129)	(7)	(160)	(56)
Unrealized net capital gains and losses, Tax	674	(105)	636	(357)
Unrecognized pension and other postretirement benefit cost arising during the period, Tax	(2)	4	(2)	8
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Tax	23	15	46	30
Unrecognized pension and other postretirement benefit cost, Tax	(25)	(11)	(48)	(22)
Unrealized foreign currency translation adjustments, Tax	12	4	18	(1)
Other comprehensive (loss) income, Tax	661	(112)	606	(380)
After-tax
Unrealized net holding gains arising during the period, net of related offsets, After-tax	(1,014)	208	(885)	774
Less: reclassification adjustment of realized capital gains and losses, After-tax	240	12	298	104
Unrealized net capital gains and losses, After-tax	(1,254)	196	(1,183)	670
Unrecognized pension and other postretirement benefit cost arising during the period, After-tax	5	(4)	7	(12)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, After-tax	(41)	(28)	(84)	(56)
Unrecognized pension and other postretirement benefit cost, After-tax	46	24	91	44
Unrealized foreign currency translation adjustments, After-tax	(21)	(7)	(33)	2
Other comprehensive (loss) income, after-tax	(1,229)	213	(1,125)	716
Net income	434	423	1,143	1,189
Comprehensive (loss) income	$ (795)	$ 636	$ 18	$ 1,905