CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 6,195	$ 5,269
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,348	15,284
Loss on sales and/or abandonment of property and equipment	288	351
Amortization of right-of-use operating lease assets	2,964
Write-off of patents and intangible assets	0	57
Acquired in-process research and development	25	0
Amortization of deferred credits	(35)	(36)
Amortization of long-term debt issuance costs	201	201
Stock-based compensation expense	1,766	1,256
Changes in operating assets and liabilities, net of effects from acquisitions:
Trade receivables	(11,557)	(13,166)
Other receivables	1,070	898
Inventories	(1,340)	(5,388)
Prepaid expenses and other current assets	19	(1,223)
Prepaid income taxes	(53)	(72)
Income tax refund receivables	(442)	(205)
Other assets	(2,092)	(491)
Trade payables	(878)	8,409
Accrued expenses	(3,450)	(2,395)
Income taxes payable	(879)	(480)
Deferred compensation payable	1,261	3
Operating lease liabilities	(3,054)
Other long-term obligations	1,148	(337)
Total adjustments	7,310	2,666
Net cash provided by operating activities	13,505	7,935
Capital expenditures for:
Property and equipment	(18,255)	(16,239)
Intangible assets	(853)	(885)
Proceeds from the sale of property and equipment	3	3
Cash paid in acquisitions, net of cash acquired	(1,942)	(100,195)
Net cash used in investing activities	(21,047)	(117,316)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	1,733	1,511
Proceeds from issuance of long-term debt	43,119	256,971
Payments on long-term debt	(54,119)	(148,971)
Contingent payments related to acquisitions	(554)	(15)
Net cash provided by (used in) financing activities	(9,821)	109,496
EFFECT OF EXCHANGE RATES ON CASH	(474)	1,720
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(17,837)	1,835
CASH AND CASH EQUIVALENTS:
Beginning of period	67,359	32,336
End of period	49,522	34,171
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $241 and $146, respectively)	2,721	2,383
Income taxes	1,934	1,810
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	4,588	$ 1,752
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	$ 1,162