Supplementary Financial Statement Information Intangibles (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	$ 59.6		$ 59.6		$ 55.9
Intangible Assets, Accumulated Amortization	(19.1)		(19.1)		(12.0)
Intangible Assets, Net Amount	40.5		40.5		43.9
Amortization of Intangible Assets	2.9	$ 2.2	7.1	$ 6.9
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	36.6		36.6		36.6
Intangible Assets, Accumulated Amortization	(11.3)		(11.3)		(7.4)
Intangible Assets, Net Amount	25.3		25.3		29.2
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross Amount	23.0		23.0		19.3
Intangible Assets, Accumulated Amortization	(7.8)		(7.8)		(4.6)
Intangible Assets, Net Amount	$ 15.2		$ 15.2		$ 14.7