Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 9,949	$ 8,713
Adjustments to reconcile net income to net cash provided by operating activities:
(Gain) loss on change in fair value of contingent consideration, net	(101)	71
Depreciation and amortization	3,206	3,475
Deferred income taxes	(433)	0
Non-cash compensation expense	3,192	2,888
Changes in other operating items:
Accounts and other receivables	7,435	805
Costs and estimated earnings in excess of billings on uncompleted contracts	(5,153)	(557)
Prepaid expenses and other current assets	(1,815)	(1,484)
Accounts payable and accrued expenses	4,732	(431)
Billings in excess of costs and estimated earnings on uncompleted contracts	(1,092)	(2,242)
Contingent consideration payments in excess of fair value on acquisition date	0	540
Other	(162)	(716)
Net cash provided by operating activities	19,758	9,982
Cash flows from investing activities:
Additions to property, plant and equipment	(1,769)	(922)
Acquisitions, net of cash acquired	(6,384)	(2,330)
Other investing activities	(844)	(1,587)
Net cash used in investing activities	(8,997)	(4,839)
Cash flows from financing activities:
Proceeds from short-term borrowings	6,727	8,585
Repayment of long-term debt	(6,000)	(6,666)
Contingent consideration payments	0	2,085
Change in negative cash book balance	(2,232)	(2,734)
Repurchases of common stock in the open market	(2,419)	(7,876)
Premium paid for interest rate cap	(474)	0
Other financing activities	(131)	26
Net cash used in financing activities	(4,529)	(10,750)
Effect of exchange rate changes on cash and cash equivalents	1,136	(563)
Net increase (decrease) in cash	7,368	(6,170)
Cash at beginning of period	16,346	21,030
Cash at end of period	23,714	14,860
Supplemental Cash Flow Information [Abstract]
Cash paid during the period for interest	906	600
Cash paid during the period for income taxes	2,806	3,910
Accrued contingent consideration	$ 4,725	$ 294