Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from operating activities	$ 8.8	$ 8.4
Reclassification to financing activities	$ 8.8	$ 8.4
Subsequent Event | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use lease assets			$ 100.0
Operating lease liability			$ 100.0