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Investments in Unconsolidated Affiliates Investments in Unconsolidated Affiliates (Hamer and Bri-Mar) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended | 9 Months Ended | 10 Months Ended | 12 Months Ended
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Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Jun. 30, 2015 | Sep. 30, 2013 | Nov. 05, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax | $ 7.1 | $ 3.9 | $ 6.8 | $ 7.3 | $ 12.3 | $ 7.0 | $ 12.5 | $ 13.8 |  |  |  | $ 25.1 | $ 45.6 | $ 36.6
Symetra |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax |  |  |  |  |  |  |  |  |  |  | $ 25.1 |  | 47.0 | 37.8
Hamer, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Realized Gain (Loss) on Disposal |  |  |  |  |  |  |  |  | $ 20.0 |  |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax |  |  |  |  |  |  |  |  | $ 1.6 |  |  |  | $ 1.9 | 0.9
Bri-Mar Manufacturing, LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Realized Gain (Loss) on Disposal |  |  |  |  |  |  |  |  |  |  |  |  |  | (1.7)
Equity in earnings of unconsolidated affiliates, net of tax |  |  |  |  |  |  |  |  |  | $ 0.9 |  |  |  |
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.1

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