CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 24,286,000	$ 11,641,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,709,000	19,705,000
Gain on bargain purchase	(11,574,000)	0
Losses on sales and/or abandonment of property and equipment	234,000	44,000
Write-off of patents and intangible assets	19,000	90,000
Acquired in-process research and development	75,000	100,000
Amortization of deferred credits	(76,000)	(85,000)
Amortization of long-term debt issuance costs	343,000	521,000
Deferred income taxes	(295,000)	141,000
Excess tax benefits from stock-based compensation	0	12,000
Stock-based compensation expense	1,691,000	1,410,000
Changes in operating assets and liabilities, net of effects from acquisitions:
Trade receivables	(13,248,000)	(6,459,000)
Employee receivables	54,000	51,000
Other receivables	(168,000)	2,126,000
Inventories	(2,160,000)	(1,403,000)
Prepaid expenses and other assets	(1,230,000)	(2,226,000)
Prepaid income taxes	(92,000)	(118,000)
Income tax refund receivables	294,000	872,000
Other assets	(1,500,000)	(762,000)
Trade payables	3,664,000	(5,147,000)
Accrued expenses	7,833,000	3,039,000
Advances from employees	(412,000)	(119,000)
Income taxes payable	(301,000)	1,620,000
Deferred compensation payable	513,000	603,000
Other long-term obligations	907,000	(212,000)
Total adjustments	10,280,000	13,803,000
Net cash provided by operating activities	34,566,000	25,444,000
Capital expenditures for:
Property and equipment	(17,782,000)	(21,222,000)
Intangible assets	(1,082,000)	(989,000)
Proceeds from sale of cost method investment	0	1,089,000
Proceeds from the sale of property and equipment	3,000	0
Cash paid in acquisitions, net of cash acquired	(54,809,000)	(22,800,000)
Net cash used in investing activities	(73,670,000)	(43,922,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	140,989,000	791,000
Payment of offering costs related to issuance of common stock	(815,000)	0
Proceeds from issuance of long-term debt	96,859,000	93,812,000
Payments on long-term debt	(179,359,000)	(69,687,000)
Excess tax benefits from stock-based compensation	0	(12,000)
Contingent payments related to acquisitions	(30,000)	(183,000)
Net cash provided by financing activities	57,644,000	24,721,000
EFFECT OF EXCHANGE RATES ON CASH	(36,000)	67,000
NET INCREASE IN CASH AND CASH EQUIVALENTS	18,504,000	6,310,000
CASH AND CASH EQUIVALENTS:
Beginning of period	19,171,000	4,177,000
End of period	37,675,000	10,487,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $240 and $194, respectively)	4,386,000	2,912,000
Income taxes	2,678,000	1,580,000
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	1,560,000	1,497,000
Acquisition purchases in accrued expenses and other long-term obligations	6,000,000	0
Contingent receivable in exchange for sale of cost method investment	$ 0	$ 681,000