CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (29,271)	$ (5,924)	$ (21,035)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation	11,737	11,287	12,971
Amortization of intangibles	3,970	8,319	8,367
Stock-based compensation	18,040	12,074	17,289
Amortization of discount on convertible and other debt	7,058	6,756	6,060
Amortization of warrant	1,746	13,576	1,178
Foreign currency adjustments	6,391	(290)	(1,906)
Loss on convertible debt extinguishment	1,362	5,695	0
Deferred income taxes, net	(105)	(2,076)	661
Provision for doubtful accounts and returns	1,666	1,500	2,521
Provision for excess and obsolete inventories	1,847	1,479	1,649
Other non-cash adjustments, net	409	1,349	1,898
Changes in operating assets and liabilities:
Accounts receivable	21,186	(8,388)	(14,700)
Inventories	(8,195)	(4,819)	(2,045)
Other assets	11,556	(3,347)	3,227
Accounts payable	(18,173)	5,086	1,018
Deferred revenues	19,751	(3,436)	(4,808)
Other liabilities	(11,812)	(7,546)	(61)
Net cash provided by operating activities	39,163	31,295	12,284
Cash flows from investing activities:
Proceeds from sales of investments	0	0	104
Purchases of property and equipment	(32,205)	(10,328)	(7,044)
Net cash used in investing activities	(32,205)	(10,328)	(6,940)
Cash flows from financing activities:
Proceeds from convertible debt	0	115,500	0
Payments of convertible debt	(7,999)	(109,603)	0
Payment of convertible debt issuance costs	(672)	(4,277)	0
Proceeds from other debts	9,398	4,684	5,066
Repayment of other debts and finance leases	(6,646)	(6,913)	(7,132)
Proceeds from common stock issued to employees	5,472	8,406	4,947
Payment of tax withholding obligations related to net share settlements of restricted stock units	(1,662)	(1,492)	(230)
Net cash (used in) provided by financing activities	(2,109)	6,305	2,651
Effect of exchange rate changes on cash and cash equivalents	738	(203)	(763)
Net increase in cash and cash equivalents	5,587	27,069	7,232
Cash and cash equivalents, beginning of the year	93,058	65,989	58,757
Cash and cash equivalents, end of the year	98,645	93,058	65,989
Supplemental disclosures of cash flow information:
Income tax payments (refunds), net	(17)	1,138	2,031
Interest payments, net	4,221	4,260	5,273
Supplemental schedule of non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	1,155	2,055	148
Fair value of warrants issued	0	16,142	2,295
Convertible Notes 2022 [Member]
Supplemental schedule of non-cash investing and financing activities:
Fair value of 2022 Notes used to settle 2020 Notes	$ 44,357	$ 0	$ 0