Acquisitions (Narrative) (Details) - USD ($)					6 Months Ended	9 Months Ended	12 Months Ended
	Aug. 28, 2018	Jul. 06, 2018	Jan. 06, 2017	Nov. 23, 2016	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life							6 years 7 months 2 days
Amortization expense							$ 16,500,000	$ 14,800,000	$ 11,200,000
Estimated future amortization expense for 2019					$ 17,700,000		17,700,000
Estimated future amortization expense for 2020					14,600,000		14,600,000
Estimated future amortization expense for 2021					13,800,000		13,800,000
Estimated future amortization expense for 2022					13,300,000		13,300,000
Estimated future amortization expense for 2023					12,700,000		$ 12,700,000
Asset acquisition, consideration transferred	$ 43,434,000
Lease, cost	45,800,000
Finance lease, principal payments	2,000,000
Asset acquisition, transaction costs	$ 400,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life							7 years 6 months 19 days
Technology
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life							4 years 4 months 7 days
Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life							2 years 1 month 6 days
Griswold
Finite-Lived Intangible Assets [Line Items]
Percentage of membership interests acquired		100.00%
Purchase price		$ 78,000,000
Cash from credit facility used to fund acquisition		82,500,000
Earn out payment		3,000,000
Actual earn out payment		0
Estimated future amortization expense for 2020						$ 2,800,000
Estimated future amortization expense for 2021						3,000,000
Estimated future amortization expense for 2022						2,800,000
Estimated future amortization expense for 2023					2,500,000	$ 2,700,000	$ 2,500,000
Business acquisition, acquiree revenue					13,700,000
Griswold | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired		22,100,000
Weighted average useful life							9 years 6 months
Griswold | Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired		9,600,000
Weighted average useful life							3 years 6 months
Griswold | Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired		1,800,000
Weighted average useful life							10 years 4 months 24 days
Griswold | Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired		$ 600,000
Weighted average useful life						3 years 2 months
Diversified Silicone Products, Inc.
Finite-Lived Intangible Assets [Line Items]
Purchase price			$ 60,200,000
Cash from credit facility used to fund acquisition			30,000,000
Estimated future amortization expense for 2019					1,800,000		$ 1,800,000
Estimated future amortization expense for 2020					1,800,000		1,800,000
Estimated future amortization expense for 2021					1,800,000		1,800,000
Estimated future amortization expense for 2022					1,700,000		1,700,000
Estimated future amortization expense for 2023					1,700,000		$ 1,700,000
Transaction costs								500,000
Business acquisition, acquiree revenue								$ 22,300,000
Diversified Silicone Products, Inc. | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired			30,500,000
Weighted average useful life							11 years 9 months 18 days
Diversified Silicone Products, Inc. | Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired			1,800,000
Weighted average useful life							4 years 3 months 18 days
Diversified Silicone Products, Inc. | Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired			3,300,000
Weighted average useful life							11 years 8 months 12 days
Diversified Silicone Products, Inc. | Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired			$ 300,000
Weighted average useful life							4 years 1 month 6 days
DeWAL
Finite-Lived Intangible Assets [Line Items]
Purchase price				$ 135,500,000
Cash from credit facility used to fund acquisition				136,000,000
Estimated future amortization expense for 2019					4,100,000		$ 4,100,000
Estimated future amortization expense for 2020					4,300,000		4,300,000
Estimated future amortization expense for 2021					4,300,000		4,300,000
Estimated future amortization expense for 2022					4,300,000		4,300,000
Estimated future amortization expense for 2023					$ 4,300,000		$ 4,300,000
Transaction costs									2,100,000
Business acquisition, acquiree revenue									$ 5,400,000
DeWAL | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired				46,700,000
Weighted average useful life							13 years 6 months
DeWAL | Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired				22,000,000
Weighted average useful life							8 years 7 months 6 days
DeWAL | Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired				4,300,000
Weighted average useful life							5 years 2 months 12 days
DeWAL | Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired				$ 500,000
Weighted average useful life							3 years 9 months 18 days
Minimum | Griswold
Finite-Lived Intangible Assets [Line Items]
Amortization expense							$ 700,000
Minimum | Diversified Silicone Products, Inc.
Finite-Lived Intangible Assets [Line Items]
Amortization expense							1,100,000
Minimum | DeWAL
Finite-Lived Intangible Assets [Line Items]
Amortization expense							2,400,000
Maximum | Griswold
Finite-Lived Intangible Assets [Line Items]
Amortization expense							3,000,000
Maximum | Diversified Silicone Products, Inc.
Finite-Lived Intangible Assets [Line Items]
Amortization expense							2,000,000
Maximum | DeWAL
Finite-Lived Intangible Assets [Line Items]
Amortization expense							4,300,000
Selling, General and Administrative Expenses | Griswold
Finite-Lived Intangible Assets [Line Items]
Transaction costs							$ 1,100,000