Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net loss	$ (11,782)	$ (17,165)
Adjustments to reconcile net loss to net cash provided by operating activities:
Change in allowance for doubtful accounts	477	1,823
Change in the fair value of acquisition-related contingent consideration	(2,063)	(1,322)
Amortization and write-off of deferred financing fees	388	388
Depreciation and amortization	25,204	24,065
Stock-based compensation	3,743	3,435
Foreign exchange loss (gain)	21	(116)
Deferred income taxes	(446)	(1,056)
Other	968
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(2,592)	(8,377)
Inventories	672	(2,255)
Prepaid expenses and other assets	(2,587)	1,861
Accounts payable and accrued liabilities	(2,418)	(13,382)
Deferred revenue	(287)	128
Other liabilities	1,637	(541)
Net cash provided by (used in) operating activities	10,935	(12,514)
Cash flows from investing activities:
Capital expenditures	(10,550)	(11,773)
Net cash used in investing activities	(10,550)	(11,773)
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
Net cash provided by financing activities	604	28,635
Effect of exchange rate changes on cash and cash equivalents	40	(151)
Net increase in cash and cash equivalents	1,029	4,197
Beginning of period	53,766	34,830
End of period	54,795	39,027
Cash paid for:
Interest	10,000	10,036
Income taxes	1,763
Noncash investing and financing activities:
Capital expenditures incurred not yet paid	854	689
Stock-based compensation related to capital expenditures	$ 458	244
Series A convertible preferred stock dividend paid in kind		$ 11