CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Cash flows from operating activities:
Net (loss) income	$ 7,601	$ (10,674)	$ (13,555)
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	13,634	21,142	22,337
(Recovery) provision for doubtful accounts	208	119	(340)
(Gain) loss on disposal of fixed assets	2,878	0	0
Stock-based compensation expense	7,958	6,258	8,311
Non-cash provision for restructuring	0	1,083	3,191
Non-cash interest expense	6,143	8,987	8,951
Unrealized foreign currency transaction losses (gains)	971	(996)	7,336
Benefit from deferred taxes	(6,309)	113	(873)
Changes in operating assets and liabilities:
Accounts receivable	(6,227)	(6,689)	3,800
Inventories	3,790	(551)	12,280
Prepaid expenses and other current assets	(44)	5,832	(7,567)
Accounts payable	626	9,148	3,606
Accrued expenses, compensation and benefits and other liabilities	(6,892)	(8,853)	(8,189)
Income taxes payable	91	38	800
Deferred revenues	(4,787)	(9,135)	(31,152)
Net cash provided by (used in) operating activities	19,641	15,822	8,936
Cash flows from investing activities:
Purchases of property and equipment	(7,185)	(9,936)	(7,877)
Increase in other long-term assets	0	19	(36)
Net cash used in investing activities	(7,185)	(9,917)	(7,913)
Cash flows from financing activities:
Proceeds from long-term debt	79,292	22,688	16,694
Repayment of debt	(1,438)	(18,451)	(6,735)
Payments for repurchase of common stock	(76,269)	0	0
Proceeds from issuance of common stock under employee stock plans	309	355	445
Common stock repurchases for tax withholdings for net settlement of equity awards	(3,586)	(998)	(1,329)
Repayments of Convertible Debt	27	(58)	0
Payments for credit facility issuance costs	(5,979)	(1,000)	(700)
Net cash provided by financing activities	(7,644)	2,536	8,375
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(331)	(780)	1,087
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	4,481	7,661	10,485
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	72,575	68,094	60,433
Supplemental information: [Abstract]
Cash and Cash Equivalents, at Carrying Value	69,085	56,103	57,223
Restricted Cash, Current	1,663	8,500	0
Restricted Cash, Noncurrent	1,827	3,491	3,210
Cash (refunded) paid for income taxes, net	(783)	(2,791)	(100)
Cash paid for interest	12,262	14,505	10,966
Non-cash transaction - property and equipment included in accounts payable or accruals	$ 23	$ 220	$ 30