Acquisitions (Details 1) - USD ($) $ in Thousands	Apr. 01, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Purchase price allocation:
Goodwill		$ 127,772	$ 121,975	$ 125,757
Effective Companies [Member]
Business Acquisition [Line Items]
Cash purchase price	$ 9,004
Fair value of contingent consideration	5,345
Total purchase price	14,349
Purchase price allocation:
Cash	334
Accounts receivable	1,378
Other assets	496
Property, plant and equipment	80
Amortizable intangible assets	1,613
Goodwill	12,556
Total assets	16,457
Accounts payable and accrued expenses	582
Billings in excess of costs and estimated earnings on uncompleted contracts	940
Deferred tax liability	586
Total liabilities	2,108
Net assets acquired	$ 14,349