Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Jul. 13, 2018	Jul. 06, 2018	Mar. 16, 2018	Mar. 09, 2018
Business Acquisition [Line Items]
Goodwill	$ 69,712	$ 67,274
Laser Control Systems
Business Acquisition [Line Items]
Accounts receivable						$ 0
Inventory						0
Other assets						0
Intangible assets						1,400
Goodwill						928
Accounts payable and accrued liabilities						0
Other liabilities						(579)
Deferred income tax liabilities						0
Total purchase price, net of cash acquired						$ 1,749
Photocore
Business Acquisition [Line Items]
Accounts receivable					$ 0
Inventory					0
Other assets					0
Intangible assets					1,435
Goodwill					1,010
Accounts payable and accrued liabilities					0
Other liabilities					0
Deferred income tax liabilities					0
Total purchase price, net of cash acquired					$ 2,445
Lanmark
Business Acquisition [Line Items]
Accounts receivable				$ 610
Inventory				299
Other assets				76
Intangible assets				1,366
Goodwill				5,355
Accounts payable and accrued liabilities				(159)
Other liabilities				(971)
Deferred income tax liabilities				(325)
Total purchase price, net of cash acquired				$ 6,251
Open Technologies
Business Acquisition [Line Items]
Accounts receivable			$ 2,735
Inventory			1,852
Other assets			634
Intangible assets			7,821
Goodwill			13,573
Accounts payable and accrued liabilities			(2,926)
Other liabilities			(5,201)
Deferred income tax liabilities	$ (1,900)		(1,876)
Total purchase price, net of cash acquired			$ 16,612