CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 4,351,000	$ 5,174,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,705,000	9,068,000
Losses on sales and/or abandonment of property and equipment	29,000	37,000
Write-off of patents and intangible assets	0	14,000
Amortization of deferred credits	(43,000)	(43,000)
Amortization of long-term debt issuance costs	257,000	247,000
Deferred income taxes	170,000	462,000
Excess tax benefits from stock-based compensation	3,000	(860,000)
Stock-based compensation expense	624,000	520,000
Changes in operating assets and liabilities, net of effects from acquisitions:
Trade receivables	(835,000)	(2,334,000)
Employee receivables	(43,000)	(6,000)
Other receivables	1,367,000	(735,000)
Inventories	(2,272,000)	3,518,000
Prepaid expenses	(498,000)	(160,000)
Prepaid income taxes	(38,000)	52,000
Income tax refund receivables	424,000	(539,000)
Other assets	109,000	(602,000)
Trade payables	2,400,000	84,000
Accrued expenses	(3,936,000)	2,653,000
Advances from employees	(388,000)	439,000
Income taxes payable	578,000	1,377,000
Deferred compensation payable	(305,000)	473,000
Other long-term obligations	(76,000)	433,000
Total adjustments	7,232,000	14,098,000
Net cash provided by operating activities	11,583,000	19,272,000
Capital expenditures for:
Property and equipment	(10,991,000)	(9,492,000)
Intangible assets	(482,000)	(495,000)
Proceeds from sale-leaseback transactions	0	1,823,000
Proceeds from the sale of property and equipment	0	3,000
Proceeds from sale of cost method investment	1,089,000	0
Cash paid in acquisitions, net of cash acquired	(21,500,000)	(1,250,000)
Net cash used in investing activities	(31,884,000)	(9,411,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	557,000	4,021,000
Proceeds from issuance of long-term debt	55,184,000	31,803,000
Payments on long-term debt	(34,376,000)	(43,415,000)
Excess tax benefits from stock-based compensation	(3,000)	860,000
Contingent payments related to acquisitions	(167,000)	(166,000)
Payment of taxes related to an exchange of common stock	0	(380,000)
Net cash provided by (used in) financing activities	21,195,000	(7,277,000)
EFFECT OF EXCHANGE RATES ON CASH	91,000	(31,000)
NET INCREASE IN CASH AND CASH EQUIVALENTS	985,000	2,553,000
CASH AND CASH EQUIVALENTS:
Beginning of period	4,177,000	7,355,000
End of period	5,162,000	9,908,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $91 and $83, respectively)	1,378,000	1,254,000
Income taxes	428,000	931,000
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	1,584,000	1,743,000
Contingent receivable received in exchange for sale of cost method investment	681,000	0
Merit common stock surrendered (0 and 89 shares, respectively) in exchange for exercise of stock options	$ 0	$ 1,725,000