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
	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