Summary of Restructuring Costs for Each Segment and Unallocated Corporate Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 2,970	$ 5,840	$ 414
2016 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring charges	3,049	3,148
Cumulative Costs	6,197
2016 Restructuring | Photonics
Restructuring Cost And Reserve [Line Items]
Restructuring charges	813	55
Cumulative Costs	868
2016 Restructuring | Vision
Restructuring Cost And Reserve [Line Items]
Restructuring charges	1,862	2,200
Cumulative Costs	4,062
2016 Restructuring | Precision Motion
Restructuring Cost And Reserve [Line Items]
Restructuring charges	106	833
Cumulative Costs	939
2016 Restructuring | Unallocated Corporate and Shared Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges	268	60
Cumulative Costs	328
2015 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring charges		1,484
2015 Restructuring | Photonics
Restructuring Cost And Reserve [Line Items]
Restructuring charges		542
2015 Restructuring | Vision
Restructuring Cost And Reserve [Line Items]
Restructuring charges		525
2015 Restructuring | Precision Motion
Restructuring Cost And Reserve [Line Items]
Restructuring charges		79
2015 Restructuring | Unallocated Corporate and Shared Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges		338
2011 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring charges	(79)	1,208	389
Cumulative Costs	5,183
2011 Restructuring | Photonics
Restructuring Cost And Reserve [Line Items]
Restructuring charges	(188)	0	(106)
Cumulative Costs	1,751
2011 Restructuring | Vision
Restructuring Cost And Reserve [Line Items]
Restructuring charges	0	0	0
Cumulative Costs	48
2011 Restructuring | Precision Motion
Restructuring Cost And Reserve [Line Items]
Restructuring charges	0	0	0
Cumulative Costs	122
2011 Restructuring | Unallocated Corporate and Shared Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges	109	$ 1,208	$ 495
Cumulative Costs	$ 3,262