Restructuring Activities - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring And Related Activities [Abstract]
Restructuring and related activities		$ 0	$ (439)	$ 6,790
Intangible Assets Reclassified as Held for Sale				$ 300
Restructuring And Related Cost Description		The 2015 Program included provisions for the reduction of total headcount by approximately 65 employees globally. As a result of this program, the Company recognized a $6.8 million restructuring charge in the fourth quarter of 2015. Employee separation costs varied depending on local regulations within certain foreign countries and included severance and other benefits. The Company substantially completed all of the initiatives under the 2015 Program in 2016 and settlement of these charges occurred primarily in 2016 as well. During the fourth quarter of 2016, the Company recognized a restructuring credit of $0.4 million in connection with the 2015 Program, due to customary and routine adjustments to initial estimates for employee separation costs, as well as the reversal of certain accrued employee separation costs as a result of the change in available-for-sale technology, noted above. The Company completed all of the remaining initiatives under the 2015 Program during the first half of 2017 and does not expect to incur further restructuring charges under this program.
Disposal Group Including Discontinued Operation Changes To Plan Of Sale	During the fourth quarter of 2016, the Company made a decision to no longer market or make available-for-sale this technology, which resulted in $0.3 million of other current assets being reclassified back to intangible assets as of December 31, 2016.