Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	$ 447.9		$ 447.9		$ 403.1
Accumulated Amortization, intangible assets subject to amortization	(201.6)		(201.6)		(184.4)
Net Carrying Amount, intangible assets subject to amortization	246.3		246.3		218.7
Amortization expense related to intangible assets subject to amortization	9.9	$ 7.8	20.0	$ 14.6
Technology
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	295.5		295.5		272.6
Accumulated Amortization, intangible assets subject to amortization	(169.4)		(169.4)		(160.5)
Net Carrying Amount, intangible assets subject to amortization	126.1		126.1		112.1
Customer relationships
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	131.7		131.7		112.0
Accumulated Amortization, intangible assets subject to amortization	(23.2)		(23.2)		(18.1)
Net Carrying Amount, intangible assets subject to amortization	108.5		108.5		93.9
Non compete contracts
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	1.8		1.8		1.8
Accumulated Amortization, intangible assets subject to amortization	(1.8)		(1.8)		(1.8)
Trade names
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	13.4		13.4		11.6
Accumulated Amortization, intangible assets subject to amortization	(2.1)		(2.1)		(1.6)
Net Carrying Amount, intangible assets subject to amortization	11.3		11.3		10.0
Other
Intangible assets
Gross Carrying Amount, intangible assets subject to amortization	5.5		5.5		5.1
Accumulated Amortization, intangible assets subject to amortization	(5.1)		(5.1)		(2.4)
Net Carrying Amount, intangible assets subject to amortization	$ 0.4		$ 0.4		$ 2.7