CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 15,874	$ (22,212)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	42,417	47,040
Loss on sales and/or abandonment of property and equipment	242	370
Write-off of certain intangible assets and other long-term assets	4,368	7,820
Amortization of right-of-use operating lease assets	6,074	6,339
Fair value adjustments to contingent consideration	2,207	5,240
Amortization of deferred credits	(54)	(69)
Amortization of long-term debt issuance costs	302	302
Stock-based compensation expense	6,732	6,205
Changes in operating assets and liabilities, net of acquisitions and divestitures:
Trade receivables	(7,833)	15,292
Other receivables	(793)	643
Inventories	3,185	2,255
Prepaid expenses and other current assets	(3,823)	(1,349)
Income tax refund receivables	(9)	(7,329)
Other assets	(685)	128
Trade payables	5,639	(3,872)
Accrued expenses	9,206	19,664
Income taxes payable	(860)	1,572
Deferred compensation payable	247	(661)
Operating lease liabilities	(6,259)	(6,177)
Other long-term obligations	263	2,015
Total adjustments	60,566	95,428
Net cash provided by operating activities	76,440	73,216
Capital expenditures for:
Property and equipment	(12,817)	(25,803)
Intangible assets	(1,469)	(1,790)
Proceeds from the sale of property and equipment	884	27
Cash received for settlement of current note receivable		250
Cash paid in acquisitions, net of cash acquired	(1,858)	(100)
Net cash used in investing activities	(15,260)	(27,416)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	11,780	3,670
Proceeds from issuance of long-term debt	32,657	38,567
Payments on long-term debt	(91,535)	(67,692)
Contingent payments related to acquisitions	(489)	(12,861)
Payment of taxes related to an exchange of common stock	(488)	(866)
Net cash used in financing activities	(48,075)	(39,182)
Effect of exchange rates on cash	(349)	(1,236)
Net increase in cash and cash equivalents	12,756	5,382
CASH AND CASH EQUIVALENTS:
Beginning of period	56,916	44,320
End of period	69,672	49,702
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $234 and $551, respectively)	2,923	5,937
Income taxes	4,611	3,808
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	1,014	1,970
Current note receivable converted to equity investment		899
Merit common stock surrendered (2 and 39 shares, respectively) in exchange for exercise of stock options	93	1,467
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	$ 361	$ 7,029