Acquisitions Schedule of recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Jan. 06, 2017	Dec. 31, 2016	Nov. 23, 2016	Jan. 22, 2015
Assets:
Goodwill	$ 237,107		$ 208,431
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
Arlon
Assets:
Cash and equivalents					$ 142
Accounts receivable					17,301
Other current assets					856
Inventory					9,916
Deferred income tax assets, current					1,084
Property, plant & equipment					30,667
Other intangible assets					50,020
Goodwill					85,565
Other long-term assets					106
Total assets					195,657
Liabilities:
Accounts payable					4,958
Other current liabilities					4,385
Deferred tax liability					23,225
Other long-term liabilities					4,540
Total liabilities					37,108
Fair value of net assets acquired					$ 158,549