Investments in Unconsolidated Affiliates (Symetra) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended									1 Months Ended	3 Months Ended
	Dec. 31, 2012 Symetra	Dec. 31, 2011 Symetra technic	Dec. 31, 2010 Symetra	Dec. 31, 2012 Common shareholders’ equity Symetra	Dec. 31, 2011 Common shareholders’ equity Symetra	Dec. 31, 2010 Common shareholders’ equity Symetra	Dec. 31, 2012 Warrants Symetra	Dec. 31, 2011 Warrants Symetra	Dec. 31, 2010 Warrants Symetra	Jan. 31, 2010 IPO Symetra	Mar. 31, 2010 IPO Symetra	Dec. 31, 2011 Minimum Symetra	Dec. 31, 2011 Maximum Symetra	Dec. 31, 2012 HG Global
Investments in unconsolidated affiliates
Shares of symetra financial corporation owned (in shares)	17,400,000
Price per share										$ 12
Investments in unconsolidated affiliates on conversion of warrants	9,500,000
Non-cumulative perpetual preference shares issued										25,300,000
Number of shares sold in transaction by existing shareholders										9,700,000
Ownership percentage before transaction											24.00%
Ownership percentage after transaction											20.00%
Decrease in carrying value of wymetra from dilution										$ 16.0
Fair value of investment		261.0
Estimated fair value of investment per share		$ 15										$ 16	$ 30
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		13.1
Ownership interest (as a percent)	15.00%													97.30%
Number of valuation techniques		3
Difference between fair value and carrying amount		195.8
Term of amortization (in years)	30 years
After tax amortization through equity in earnings	3.3
After tax amortization through equity in net unrealized losses	12.1
Pre-tax unamortized basis difference	179.2
Risk free interest rate (as a percent)	0.21%
Volatility rate (as a percent)	38.90%
Expected life (in years)	1 year 7 months 6 days
Class of warrant or right fair value assumptions per strike price	$ 11.49
Per share price, class of warrant (in dollars per share)														$ 12.98
Divendends received	4.9	4.0	2.6	4.9	4.0	2.6	0	0	0
Cash dividends received on warrants							$ 2.7