Supplementary Financial Statement Information (Details4) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill balance	$ 253.8
Adjustment to acquisition purchase price	1.2
Goodwill balance	255.0
Intangible Assets, Gross Amount	56.9	$ 56.9
Intangible Assets, Accumulated Amortization	(6.2)	(4.0)
Intangible Assets, Net Amount	50.7	52.9
Amortization of Intangible Assets	2.4
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	36.6	36.6
Intangible Assets, Accumulated Amortization	(3.5)	(2.2)
Intangible Assets, Net Amount	33.1	34.4
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	19.3	19.3
Intangible Assets, Accumulated Amortization	(2.1)	(1.4)
Intangible Assets, Net Amount	17.2	17.9
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	1.0	1.0
Intangible Assets, Accumulated Amortization	(0.6)	(0.4)
Intangible Assets, Net Amount	$ 0.4	$ 0.6