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Investments in Unconsolidated Affiliates (Symetra Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended |  | 12 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | 1 Months Ended | 3 Months Ended |  | 6 Months Ended |  |
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 Symetra | Dec. 31, 2012 Symetra | Dec. 31, 2011 Symetra technique | Jun. 20, 2013 Symetra | Dec. 31, 2013 Common Stock Symetra | Dec. 31, 2012 Common Stock Symetra | Dec. 31, 2011 Common Stock Symetra | Jun. 30, 2013 Warrants | Jun. 20, 2013 Warrants | Jun. 20, 2013 Warrants Symetra | Dec. 31, 2013 Warrants Symetra | Dec. 31, 2012 Warrants Symetra | Dec. 31, 2011 Warrants Symetra | Jan. 31, 2010 IPO Symetra | Mar. 31, 2010 IPO Symetra | Dec. 31, 2011 Minimum Symetra | Dec. 31, 2011 Maximum Symetra | Jun. 20, 2013 Symetra Common Stock | Jun. 20, 2013 equity in earnings of unconsolidated affiliates [Member] Symetra | Jun. 20, 2013 Net unrealized gains (losses) of unconsolidated affiliates [Member] Symetra | Dec. 31, 2011 Best Estimate [Member] Symetra
Investments in unconsolidated affiliates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares of symetra financial corporation owned (in shares) |  |  |  | 20,050,000 | 17,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.00 |  |  |  |  |  |  |
Investments in unconsolidated affiliates on conversion of warrants |  |  |  |  | 9,490,000 |  | 2,650,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  | $ 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 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest (as a percent) |  |  |  | 17.03% | 14.60% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of valuation techniques |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Term of amortization (in years) |  |  |  |  |  | 30 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weight Average Years Remaining |  |  |  | 29 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
After tax amortization through equity in earnings |  |  |  | 2.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
After tax amortization through equity in net unrealized losses |  |  |  | 10.8 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity |  |  |  | 183.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk free interest rate (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  | 0.34% |  |  |  |  |  |  |  |  |  |  |
Volatility rate (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  | 26.50% |  |  |  |  |  |  |  |  |  |  |
Per share price, class of warrant (in dollars per share) |  |  |  |  |  |  |  | $ 18.96 |  |  |  |  | $ 15.53 |  |  |  |  |  |  |  |  |  |  |
Cash dividends received on warrants |  |  |  |  |  |  |  |  |  |  |  |  | 1.5 |  |  |  |  |  |  |  |  |  |  |
Fair Value Assumptions, Expected Term |  |  |  |  |  |  |  |  |  |  |  |  | 1 year 1 month 10 days |  |  |  |  |  |  |  |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights |  |  |  |  |  |  |  |  |  |  |  |  | 11.49 |  |  |  |  |  |  |  |  |  |  |
Common shares repurchased and retired during the period |  | 1,329,640 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,600,000 |  |  |
Treasury Stock Acquired, Average Cost Per Share | $ 564.00 | $ 503.00 | $ 390.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 13.44 |  |  |
Unamortized basis difference |  |  |  |  |  |  | 19.3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.4 | 18.9 |
Gain (Loss) on Warrants |  |  |  | 10.8 | 17.7 | (24.5) |  | 0 | 0 | 0 | 14.5 | 10.8 |  | 10.8 | 17.7 | (24.5) |  |  |  |  |  |  |  |
Dividends received |  |  |  | $ (6.4) | $ (4.9) | $ (4.0) |  | $ (6.4) | $ (4.9) | $ (4.0) |  |  |  | $ 0 | $ 0 | $ 0 |  |  |  |  |  |  |  |

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