Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Accumulated Other Comprehensive Income (Loss)	Mar. 31, 2012 Accumulated Other Comprehensive Income (Loss)	Mar. 31, 2013 Accumulated Net Unrealized Investment Gain (Loss)	Mar. 31, 2012 Accumulated Net Unrealized Investment Gain (Loss)	Mar. 31, 2013 Accumulated Defined Benefit Plans Adjustment	Mar. 31, 2012 Accumulated Defined Benefit Plans Adjustment	Mar. 31, 2013 Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other	Mar. 31, 2012 Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale, before tax, beginning of period					$ 1,875	$ 1,489
Other comprehensive income before reclassification, before tax					397	241	0	0
Reclassification adjustment for realized gains, net, included in net income, before tax					(41)	(13)
Effect on other comprehensive income, before tax					356	228
Accumulated unrealized gains, net, on investments available for sale, before tax, end of period					2,231	1,717
Accumulated unrealized losses, net, for pension obligations, before Tax, beginning of period							(101)	(88)
Reclassification adjustment for amortization of actuarial loss and prior service cost, net, included in net income, before tax							2	2
Effect on other comprehensive income, before tax							2	2
Accumulated unrealized losses, net, for pension obligations, before Tax, end of period							(99)	(86)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, beginning of period									(50)	(29)
Effect on other comprehensive income, before tax									0	(5)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, end of period									(50)	(34)
Accumulated other comprehensive income, before taxes, beginning of period			1,724	1,372
Change in unrealized gains, net, on investments available for sale, before Tax			356	228
Change in pension obligations, before tax			2	2
Change in life deferred acquisition costs, life policy reserves and other, before Tax			0	(5)
Effect on other comprehensive income, before Tax			358	225
Accumulated other comprehensive income, before taxes, end of period			2,082	1,597
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, beginning of period					771	592
Other comprehensive income before reclassification, tax					139	84	0	0
Reclassification adjustment for realized gains, net, included in net income, tax					(15)	(4)
Effect on other comprehensive income, tax					124	80
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, end of period					647	512
Accumulated unrealized losses, net, for pension obligations, tax, beginning of period							(35)	(31)
Reclassification adjustment for amortization of actuarial loss and prior service cost, net, included in net income, tax							1	1
Effect on other comprehensive income, tax							1	1
Accumulated unrealized losses, net, for pension obligations, tax, end of period							(34)	(30)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, beginning of period									(17)	(10)
Effect on other comprehensive income, tax									0	(2)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, end of period									(17)	(12)
Accumulated other comprehensive income, tax, beginning of period			595	471
Change in unrealized gains, net, on investments available for sale and other invested assets, tax			124	80
Change in pension obligations, tax			1	1
Change in life deferred acquisition costs, life policy reserves and other, tax			0	(2)
Effect on other comprehensive income, tax			125	79
Accumulated other comprehensive income, tax, end of period			720	550
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, beginning of period					1,228	977
Other comprehensive income before reclassification , net of tax					258	157	0	0
Reclassification adjustment for realized gains, net, included in net income, net of tax					(26)	(9)
Effect on other comprehensive income, net of tax					232	148
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, end of period					1,460	1,125
Accumulated unrealized losses, net, for pension obligations, net of tax, beginning of period							(66)	(57)
Reclassification adjustment for amortization of actuarial loss and prior service cost,net, included in net income, net of tax							1	1
Effect on other comprehensive income, net of tax							1	1
Accumulated unrealized losses, net, for pension obligations, net of tax, end of period							(65)	(56)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, beginning of period, net of tax									(33)	(19)
Effect on other comprehensive income, net of tax									0	(3)
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, end of period, net of tax									(33)	(22)
Accumulated other comprehensive income, net of tax, beginning of period	1,362	1,129	1,129	901
Change in unrealized gains, net, on investments available for sale, net of tax			232	148
Change in pension obligations, net of tax			1	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax			0	(3)
Effect on other comprehensive income, net of tax			233	146
Accumulated other comprehensive income, net of tax, end of period	$ 1,362	$ 1,129	$ 1,362	$ 1,047