Income Taxes (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Deferred Tax Assets Liabilities Net
Net deferred tax liability	$ 103	$ 283
Percent of total permanent tax differences related to investment revenues (as a percent)	98.00%
Indemnity
Deferred Tax Assets Liabilities Net
Net deferred tax liability	6	26
Effective Tax Rate when investment permanent tax differences are excluded (as a percent)	35.00%
Exchange
Deferred Tax Assets Liabilities Net
Net deferred tax liability	$ 97	$ 257
Effective Tax Rate when investment permanent tax differences are excluded (as a percent)	35.00%