Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (15,651)	$ (20,387)
Adjustments to reconcile net loss to net cash provided by operating activities:
Change in allowance for doubtful accounts	1,766	2,995
Change in the fair value of acquisition-related contingent consideration	(2,063)	(5,494)
Amortization and write-off of deferred financing fees	582	582
Depreciation and amortization	37,998	36,146
Stock-based compensation	5,406	5,747
Foreign exchange (gain) loss	(194)	64
Deferred income taxes	(1,097)	(1,847)
Other	1,971
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(5,972)	(14,490)
Inventories	(3,973)	5,554
Prepaid expenses and other assets	(3,338)	601
Accounts payable and accrued liabilities	6,960	(11,493)
Deferred revenue	(348)	1,687
Other liabilities	(1,246)	(595)
Net cash provided by (used in) operating activities	20,801	(930)
Cash flows from investing activities:
Capital expenditures	(16,234)	(17,163)
Other		650
Net cash used in investing activities	(16,234)	(16,513)
Cash flows from financing activities:
Proceeds from public offering of common stock, net of underwriters’ discounts and commissions and offering costs of $1,705		27,967
Payments under revolving credit facility		(14,000)
Proceeds under revolving credit facility		14,000
Proceeds from issuance of common stock under employee stock purchase plan	604	668
Purchases of common stock under share repurchase program	(7,875)
Net cash (used in) provided by financing activities	(7,271)	28,635
Effect of exchange rate changes on cash and cash equivalents	(158)	(128)
Net (decrease) increase in cash and cash equivalents	(2,862)	11,064
Beginning of period	53,766	34,830
End of period	50,904	45,894
Cash paid for:
Interest	10,000	10,036
Income taxes	2,439	3,221
Noncash investing and financing activities:
Capital expenditures incurred not yet paid	785	332
Stock-based compensation related to capital expenditures	539	410
Series A convertible preferred stock dividend paid-in-kind	12	11
Common stock issued as payment for MPUs	$ 502	$ 827