Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 13,230	$ 13,515
Adjustments to reconcile net income to net cash provided by operating activities:
(Gain) loss on change in fair value of contingent consideration, net	(369)	74
Depreciation and amortization	5,153	4,969
Deferred income taxes	(421)	(1,596)
Non-cash compensation expense	4,876	4,456
Changes in other operating items:
Accounts and other receivables	11,805	(1,054)
Costs and estimated earnings in excess of billings on uncompleted contracts	(11,670)	(8,655)
Prepaid expenses and other current assets	(6,232)	(4,793)
Accounts payable and accrued expenses	8,145	10,791
Billings in excess of costs and estimated earnings on uncompleted contracts	(3,203)	(4,361)
Contingent consideration payments in excess of fair value on acquisition date	0	(540)
Other	(140)	(908)
Net cash provided by operating activities	21,174	11,898
Cash flows from investing activities:
Additions to property, plant and equipment	(2,324)	(1,184)
Acquisitions, net of cash acquired	(11,112)	(2,161)
Other investing activities	(981)	(2,037)
Net cash used in investing activities	(14,417)	(5,382)
Cash flows from financing activities:
Proceeds from short-term borrowings	9,749	10,765
Repayment of long-term debt	(9,000)	(10,000)
Contingent consideration payments	(967)	(2,085)
Change in negative cash book balance	(2,813)	(1,651)
Tax withholding payments for employee stock-based compensation in exchange for shares surrendered	(604)	(400)
Repurchases of common stock in the open market	(2,419)	(7,959)
Premium paid for interest rate cap	(474)	0
Other financing activities	120	175
Net cash used in financing activities	(6,408)	(11,155)
Effect of exchange rate changes on cash and cash equivalents	1,325	(696)
Net increase (decrease) in cash	1,674	(5,335)
Cash at beginning of period	16,346	21,030
Cash at end of period	18,020	15,695
Supplemental Cash Flow Information [Abstract]
Cash paid during the period for interest	1,381	947
Cash paid during the period for income taxes	4,874	6,228
Accrued contingent consideration	$ 5,613	$ 410