Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Apr. 30, 2017	Dec. 31, 2016	Aug. 31, 2016	Jul. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 52,567		$ 46,744
BuildIT
Business Acquisition [Line Items]
Accounts receivable					$ 237
Inventory					0
Other assets					36
Deferred income tax assets					0
Intangible assets					1,015
Goodwill					3,393
Accounts payable and accrued liabilities					(95)
Other liabilities					(471)
Deferred income tax liabilities					(205)
Total purchase price, net of cash acquired					$ 3,910
LPT
Business Acquisition [Line Items]
Accounts receivable				$ 54
Inventory				322
Other assets				160
Deferred income tax assets				1,112
Intangible assets				5,474
Goodwill				11,922
Accounts payable and accrued liabilities				(747)
Other liabilities				(1,086)
Deferred income tax liabilities				0
Total purchase price, net of cash acquired				$ 17,211
MWF
Business Acquisition [Line Items]
Accounts receivable			150
Inventory			0
Other assets			666
Deferred income tax assets			0
Intangible assets			1,816
Goodwill			5,364
Accounts payable and accrued liabilities			(700)
Other liabilities			(345)
Deferred income tax liabilities			(364)
Total purchase price, net of cash acquired			$ 6,587
Nutfield
Business Acquisition [Line Items]
Accounts receivable		$ 160
Inventory		539
Other assets		96
Deferred income tax assets		0
Intangible assets		2,329
Goodwill		2,488
Accounts payable and accrued liabilities		(12)
Other liabilities		(104)
Deferred income tax liabilities		0
Total purchase price, net of cash acquired		$ 5,496