Revenue, Gross Profit and Operating Income (Loss) by Reportable Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 626,099	$ 614,337	$ 521,290
Gross Profit	262,085	261,528	220,531
Operating Income (Loss)	55,282	71,013	57,566
Operating Segments | Photonics
Segment Reporting Information [Line Items]
Revenue	230,457	249,339	232,359
Gross Profit	105,845	117,109	106,117
Operating Income (Loss)	41,990	59,285	51,660
Operating Segments | Vision
Segment Reporting Information [Line Items]
Revenue	271,407	232,902	183,074
Gross Profit	105,228	87,198	69,249
Operating Income (Loss)	21,007	8,991	7,883
Operating Segments | Precision Motion
Segment Reporting Information [Line Items]
Revenue	124,235	132,096	105,857
Gross Profit	53,326	59,477	46,564
Operating Income (Loss)	22,339	31,674	27,146
Unallocated Corporate and Shared Services
Segment Reporting Information [Line Items]
Gross Profit	(2,314)	(2,256)	(1,399)
Operating Income (Loss)	$ (30,054)	$ (28,937)	$ (29,123)