Acquisitions - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Feb. 08, 2018	Dec. 31, 2017	May 31, 2017
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill	$ 1,554,830		$ 1,478,257
Snell Advanced Media
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Receivables		$ 17,182
Inventory		15,312
Prepaid and other current assets		3,375
Property, plant, and equipment		7,789
Intangible assets		54,100
Goodwill		87,853
Deferred taxes		5,476
Other long-lived assets		2,156
Total assets acquired		193,243
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable		11,927
Accrued liabilities		21,614
Deferred revenue		3,924
Long-term debt		19,315
Postretirement benefits		31,343
Other long-term liabilities		591
Total liabilities assumed		88,714
Net assets		$ 104,529
Thinklogical Holdings LLC
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Receivables				$ 4,355
Inventory				16,424
Prepaid and other current assets				320
Property, plant, and equipment				4,289
Intangible assets				73,400
Goodwill				70,654
Deferred income taxes				598
Total assets acquired				170,040
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable				1,231
Accrued liabilities				1,353
Deferred revenue				1,702
Total liabilities assumed				4,286
Net assets				$ 165,754