Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets, Pre-tax	$ 730	$ 211
Less: reclassification adjustment of realized capital gains and losses, Pre-tax	46	102
Unrealized net capital gains and losses, Pre-tax	684	109
Unrecognized pension and other postretirement benefit cost arising during the period, Pre-tax	4	2
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Pre-tax	(13)	(66)
Unrecognized pension and other postretirement benefit cost, Pre-tax	17	68
Unrealized foreign currency translation adjustments, Pre-tax	(25)	(18)
Other comprehensive income, Pre-tax	676	159
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets, Tax	(255)	(74)
Less: reclassification adjustment of realized capital gains and losses, Tax	(16)	(36)
Unrealized net capital gains and losses, Tax	(239)	(38)
Unrecognized pension and other postretirement benefit cost arising during the period, Tax	(1)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, Tax	5	23
Unrecognized pension and other postretirement benefit cost, Tax	(6)	(23)
Unrealized foreign currency translation adjustments, Tax	9	6
Other comprehensive income, Tax	(236)	(55)
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets, After-tax	475	137
Less: reclassification adjustment of realized capital gains and losses, After-tax	30	66
Unrealized net capital gains and losses, After-tax	445	71
Unrecognized pension and other postretirement benefit cost arising during the period, After-tax	3	2
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses, After-tax	(8)	(43)
Unrecognized pension and other postretirement benefit cost, After-tax	11	45
Unrealized foreign currency translation adjustments, After-tax	(16)	(12)
Other comprehensive income, after-tax	440	104
Net income	600	709
Comprehensive income	$ 1,040	$ 813