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Investments in Unconsolidated Affiliates (Symetra) (Details) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended | 1 Months Ended | 3 Months Ended |  |
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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 |  |  |  |  |  |  |

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