Business Combinations (Narrative) (Details) - USD ($) $ in Millions			3 Months Ended	9 Months Ended
	May 31, 2018	Jan. 02, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Purchase price, net of cash acquired				$ 98.6	$ 163.8
Goodwill			$ 650.1	650.1		$ 610.5
IQAP
Business Acquisition [Line Items]
Purchase price, net of cash acquired		$ 73.0
Intangible assets acquired		31.9
Goodwill		24.5
Property, plant and equipment		24.1
Other liabilities		20.8
Net working capital acquired		$ 13.3
Sales from companies acquired since acquisition date			14.1	47.1
PlastiComp
Business Acquisition [Line Items]
Purchase price, net of cash acquired	$ 44.6
Intangible assets acquired	19.1
Goodwill	$ 16.6
Sales from companies acquired since acquisition date			$ 5.0	$ 7.2
Earn-out period	2 years
Minimum | IQAP
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		13 years
Minimum | PlastiComp
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years
Maximum | IQAP
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		20 years
Maximum | PlastiComp
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	24 years