CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Cash flows from operating activities:
Net (loss) income	$ 11,062	$ 7,601	$ (10,674)
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	8,505	13,634	21,142
(Recovery) provision for doubtful accounts	1,298	208	119
(Gain) loss on disposal of fixed assets	0	2,878	0
Stock-based compensation expense	10,664	7,958	6,258
Non-cash provision for restructuring	5,046	0	1,083
Non-cash interest expense	3,651	6,143	8,987
Unrealized foreign currency transaction losses (gains)	1,570	971	(996)
Benefit from deferred taxes	827	(6,309)	113
Changes in operating assets and liabilities:
Accounts receivable	(6,124)	(6,227)	(6,689)
Inventories	2,598	3,790	(551)
Prepaid expenses and other current assets	6,176	(44)	5,832
Accounts payable	(18,141)	626	9,148
Accrued expenses, compensation and benefits and other liabilities	10,432	(6,892)	(8,853)
Income taxes payable	(281)	91	38
Deferred revenues	2,272	(4,787)	(9,135)
Net cash provided by (used in) operating activities	39,555	19,641	15,822
Cash flows from investing activities:
Purchases of property and equipment	(5,692)	(7,185)	(9,936)
Increase in other long-term assets	0	0	19
Net cash used in investing activities	(5,692)	(7,185)	(9,917)
Cash flows from financing activities:
Proceeds from revolving credit facilities	22,000	0	0
Payments on revolving credit facilities	(22,000)	0	0
Proceeds from long-term debt	7,800	79,292	22,688
Repayment of debt	(2,250)	(1,438)	(18,451)
Payments for repurchase of common stock	(28,867)	(76,269)	0
Proceeds from issuance of common stock under employee stock plans	547	309	355
Common stock repurchases for tax withholdings for net settlement of equity awards	(2,365)	(3,586)	(998)
Repayments of Convertible Debt	875	27	58
Payments for credit facility issuance costs	(289)	(5,979)	(1,000)
Net cash provided by financing activities	(24,549)	(7,644)	2,536
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	1,748	(331)	(780)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	11,062	4,481	7,661
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	83,637	72,575	68,094
Supplemental information: [Abstract]
Cash and Cash Equivalents, at Carrying Value	79,899	69,085	56,103
Restricted Cash, Current	1,422	1,663	8,500
Restricted Cash, Noncurrent	2,316	1,827	3,491
Cash (refunded) paid for income taxes, net	(391)	783	(2,791)
Cash paid for interest	17,499	12,262	14,505
Non-cash transaction - property and equipment included in accounts payable or accruals	$ 0	$ 23	$ 220