Revenue, Gross Profit and Operating Income (Loss) by Reportable Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 614,337	$ 521,290	$ 384,758
Gross Profit	261,528	220,531	162,452
Operating Income (Loss)	71,013	57,566	32,955
Unallocated Corporate and Shared Services
Segment Reporting Information [Line Items]
Gross Profit	(2,256)	(1,399)	(1,469)
Operating Income (Loss)	(28,937)	(29,123)	(22,086)
Photonics
Segment Reporting Information [Line Items]
Revenue	249,339	232,359	174,158
Photonics | Operating Segments
Segment Reporting Information [Line Items]
Gross Profit	117,109	106,117	76,696
Operating Income (Loss)	59,285	51,660	35,217
Vision
Segment Reporting Information [Line Items]
Revenue	232,902	183,074	122,250
Vision | Operating Segments
Segment Reporting Information [Line Items]
Gross Profit	87,198	69,249	47,181
Operating Income (Loss)	8,991	7,883	(1,277)
Precision Motion
Segment Reporting Information [Line Items]
Revenue	132,096	105,857	88,350
Precision Motion | Operating Segments
Segment Reporting Information [Line Items]
Gross Profit	59,477	46,564	40,044
Operating Income (Loss)	$ 31,674	$ 27,146	$ 21,101