Goodwill and Other Intangible Assets - Other Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amortization of Intangible Assets [Line Items]
Amortization of intangible assets	$ 19,920	$ 20,470	$ 20,970
Continuing Operations [Member]
Amortization of Intangible Assets [Line Items]
Amortization of intangible assets	19,920	20,470	20,970
Continuing Operations [Member] | Cost of Sales [Member] | Technology and Other [Member]
Amortization of Intangible Assets [Line Items]
Amortization of intangible assets	5,340	5,680	6,010
Continuing Operations [Member] | Selling, General and Administrative Expenses [Member] | Customer Relationships [Member]
Amortization of Intangible Assets [Line Items]
Amortization of intangible assets	$ 14,580	$ 14,790	$ 14,960