Investments in Unconsolidated Affiliates (Details 2) (Symetra, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			9 Months Ended	1 Months Ended
	Mar. 31, 2010	Sep. 30, 2011 Common shareholders' equity	Dec. 31, 2010 Common shareholders' equity	Sep. 30, 2011 Warrants	Jan. 31, 2010 Initial public offering
Investments in unconsolidated affiliates
Investments in unconsolidated affiliates (in shares)		17,400,000	17,400,000
Additional common shares (in shares)		9,500,000	9,500,000
Risk free interest rate (as a percent)				0.37%
Volatility rate (as a percent)				31.64%
Expected life (in years)				2.83Y
Strike price (in dollars per share)				$ 11.49
Share price (in dollars per share)				$ 8.15
Initial public offering issue price (in dollars per share)					$ 12.00
Sale of Symetra common shares by Symetra (in shares)					25,300,000
Sale of Symetra common shares by existing shareholders (in shares)					9,700,000
Ownership interest after initial public offering (as a percent)	20.00%
Decrease in carrying value of Symetra from dilution	$ 16.0