Acquisitions (Details Textual) $ in Thousands				12 Months Ended
	Oct. 01, 2016 USD ($)	Mar. 01, 2016 USD ($)	Apr. 01, 2014 USD ($) period	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life				2 years 5 months
Goodwill				$ 127,772	$ 121,975	$ 125,757
Contingent consideration payments				(2,244)	(2,284)	$ (977)
Accounts payable and accrued liability				3,600	2,400
Business acquisition contingent consideration, other long term liability				1,700
Jencal Training [Member]
Business Acquisition [Line Items]
Cash purchase price		$ 2,500
Additional consideration contingent on achieving certain earnings targets		200
Goodwill		1,800
Jencal Training [Member] | Intangible Assets [Member]
Business Acquisition [Line Items]
Amortizable intangible assets		$ 1,400
Acquired finite-lived intangible assets, weighted average useful life		4 years
Maverick Solutions [Member]
Business Acquisition [Line Items]
Cash purchase price	$ 4,639
Additional consideration contingent on achieving certain earnings targets	10,000
Goodwill	$ 8,111
Effective Companies [Member]
Business Acquisition [Line Items]
Cash purchase price			$ 9,004
Additional consideration contingent on achieving certain earnings targets			5,700
Amortizable intangible assets			1,613
Goodwill			$ 12,556
Number of earning target periods | period			2
Payments on contingent consideration liability					$ 2,600
Contingent consideration payments				$ (2,600)
Effective Companies [Member] | Intangible Assets [Member]
Business Acquisition [Line Items]
Amortizable intangible assets			$ 1,600
Acquired finite-lived intangible assets, weighted average useful life			4 years