CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 14,803,000	$ 4,351,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,759,000	9,705,000
Gain on bargain purchase	(12,243,000)	0
Losses on sales and/or abandonment of property and equipment	212,000	29,000
Write-off of patents and intangible assets	18,000	0
Amortization of deferred credits	(40,000)	(43,000)
Amortization of long-term debt issuance costs	171,000	257,000
Deferred income taxes	(387,000)	170,000
Excess tax benefits from stock-based compensation	0	3,000
Stock-based compensation expense	577,000	624,000
Changes in operating assets and liabilities, net of effects from acquisitions:
Trade receivables	(5,757,000)	(835,000)
Employee receivables	36,000	(43,000)
Other receivables	374,000	1,367,000
Inventories	844,000	(2,272,000)
Prepaid expenses and other assets	229,000	(498,000)
Prepaid income taxes	(89,000)	(38,000)
Income tax refund receivables	(350,000)	424,000
Other assets	(1,172,000)	109,000
Trade payables	1,039,000	2,400,000
Accrued expenses	3,285,000	(3,936,000)
Advances from employees	(86,000)	(388,000)
Income taxes payable	(22,000)	578,000
Deferred compensation payable	187,000	(305,000)
Other long-term obligations	790,000	(76,000)
Total adjustments	375,000	7,232,000
Net cash provided by operating activities	15,178,000	11,583,000
Capital expenditures for:
Property and equipment	(10,178,000)	(10,991,000)
Intangible assets	(668,000)	(482,000)
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	(47,461,000)	(21,500,000)
Net cash used in investing activities	(58,304,000)	(31,884,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	138,569,000	557,000
Payment of offering costs related to issuance of common stock	(833,000)	0
Proceeds from issuance of long-term debt	83,723,000	55,184,000
Payments on long-term debt	(170,723,000)	(34,376,000)
Excess tax benefits from stock-based compensation	0	(3,000)
Contingent payments related to acquisitions	(15,000)	(167,000)
Net cash provided by financing activities	50,721,000	21,195,000
EFFECT OF EXCHANGE RATES ON CASH	(302,000)	91,000
NET INCREASE IN CASH AND CASH EQUIVALENTS	7,293,000	985,000
CASH AND CASH EQUIVALENTS:
Beginning of period	19,171,000	4,177,000
End of period	26,464,000	5,162,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $119 and $91, respectively)	2,743,000	1,378,000
Income taxes	1,571,000	428,000
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	756,000	1,584,000
Contingent receivable in exchange for sale of cost method investment	$ 0	$ 681,000