Acquisitions (Schedule of Recognized Identified Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 06, 2018	Dec. 31, 2017	Jan. 06, 2017	Nov. 23, 2016
Assets:
Goodwill	$ 264,885		$ 237,107
Griswold
Assets:
Accounts receivable		$ 2,553
Other current assets		155
Inventory		2,951
Property, plant & equipment		7,554
Other intangible assets		34,120
Goodwill		31,738
Total assets		79,071
Liabilities:
Accounts payable		711
Accrued employee benefits and compensation		299
Other accrued liabilities		92
Total liabilities		1,102
Fair value of net assets acquired		$ 77,969
Diversified Silicone Products, Inc.
Assets:
Accounts receivable				$ 2,724
Prepaid expenses				21
Inventory				2,433
Property, plant & equipment				1,589
Other intangible assets				35,860
Goodwill				17,793
Total assets				60,420
Liabilities:
Accounts payable				179
Accrued expenses				50
Total liabilities				229
Fair value of net assets acquired				$ 60,191
DeWAL
Assets:
Cash and equivalents					$ 1,539
Accounts receivable					7,513
Other current assets					691
Inventory					9,915
Property, plant & equipment					9,932
Other intangible assets					73,500
Goodwill					35,985
Other long-term assets					101
Total assets					139,176
Liabilities:
Accounts payable					2,402
Other current liabilities					1,292
Total liabilities					3,694
Fair value of net assets acquired					$ 135,482