Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 16, 2018	Mar. 09, 2018	Dec. 31, 2017	Apr. 30, 2017
Business Acquisition [Line Items]
Goodwill	$ 53,584			$ 52,750
Nutfield (Final)
Business Acquisition [Line Items]
Accounts receivable					$ 160
Inventory					539
Other assets					96
Deferred income tax assets					131
Intangible assets					2,329
Goodwill					2,357
Accounts payable and accrued liabilities					(12)
Other liabilities					(104)
Total purchase price, net of cash acquired					$ 5,496
Laser Control Systems Limited
Business Acquisition [Line Items]
Accounts receivable			$ 0
Inventory			0
Other assets			0
Deferred income tax assets			0
Intangible assets			1,400
Goodwill			928
Accounts payable and accrued liabilities			0
Other liabilities			(579)
Total purchase price, net of cash acquired			$ 1,749
Photocore AG
Business Acquisition [Line Items]
Accounts receivable		$ 0
Inventory		0
Other assets		0
Deferred income tax assets		0
Intangible assets		1,435
Goodwill		1,010
Accounts payable and accrued liabilities		0
Other liabilities		0
Total purchase price, net of cash acquired		$ 2,445