Investments in Unconsolidated Affiliates (Symetra) (Details) (Symetra, USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Y Year	Sep. 30, 2011	Dec. 31, 2011
Investments in unconsolidated affiliates
Shares of Symetra Financial Corporation owned (in shares)	17.4		17.4		17.4
Investments in unconsolidated affiliates on conversion of warrants	9.5		9.5		9.5
Fair value of investment					$ 261.0
Estimated fair value of investment per share					$ 15
After-tax equity in losses of unconsolidated affiliates					45.9
Equity in net unrealized losses increase relating to amortization of common share impairment					136.6
Equity in Unrealized Gains (Losses) from Investments in Unconsolidated Affiliates	35.2	147.7	64.6	147.7	0
Ownership interest (as a percent)	15.00%		15.00%
Difference between fair value and carrying amount					195.8
Term of amortization (in years)			30
After tax amortization through equity in earnings	0.8		2.4
After tax amortization through equity in net unrealized losses	3.0		9.1
Pre-tax unamortized basis difference	183.3		183.3
Risk free interest rate (as a percent)			0.22%
Volatility rate (as a percent)			36.50%
Expected life (in years)			1.82
Class of warrant or right fair value assumptions per strike price	$ 11.49		$ 11.49
Market Price Per Share	$ 12.30		$ 12.30
Common Stock
Investments in unconsolidated affiliates
Equity in net unrealized losses increase relating to amortization of common share impairment	$ 3.3		$ 9.9