Shareholders' Equity (Details) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Accumulated other comprehensive income (loss), net of tax
Pretax Net Unrealized Gains (Losses) on Securities, Beginning Balance	$ 736	$ 258
Foreign Currency Translation Adjustment, Beginning Balance	9	1
Pension and Other Postretirement Plans Adjustment, Beginning Balance	(13)	(13)
Tax Effects, Beginning Balance	(253)	(86)
Non-controlling Interest, Beginning Balance	0	3
Accumulated Other Comprehensive Income (Loss), Beginning Balance	479	163
Unrealized holding gains (losses) on securities arising during the period, before tax	199	778
Unrealized holding gains (losses) on securities arising during the period, tax	(70)	(272)
Unrealized holding gains (losses) on securities arising during the period, net of tax, attributable to non-controlling interests	(5)	(7)
Unrealized holding gains (losses) on securities arising during the period, net of tax	124	499
Realized gains included in net income, before tax	(53)	(92)
Realized gains included in net income, tax	19	32
Realized gains included in net income, net of tax, attributable to non-controlling interests	1	1
Realized gains included in net income, net of tax	(33)	(59)
Foreign currency translation gains (losses), before tax	(9)	9
Foreign currency translation gains (losses), net of tax, attributable to non-controlling interests	1	(2)
Foreign currency translation gains (losses), net of tax	(8)	7
Other changes in net unrealized gains (losses) on securities, before tax		(6)
Other changes in pension and other postretirement plans, before tax	1	1
Other, tax		2
Other, net of tax	1	(3)
Pretax Net Unrealized Gains (Losses) on Securities, Ending Balance	882	938
Foreign Currency Translation Adjustment, Ending Balance	0	10
Pension and Other Postretirement Plans Adjustment, Ending Balance	(12)	(12)
Tax Effects, Ending Balance	(304)	(324)
Non-controlling Interest, Ending Balance	(3)	(5)
Accumulated Other Comprehensive Income (Loss), Ending Balance	$ 563	$ 607