CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Cash flows from operating activities:
Net (loss) income	$ (10,674)	$ (13,555)	$ 48,219
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	21,142	22,337	25,479
(Recovery) provision for doubtful accounts	119	(340)	886
Stock-based compensation expense	6,258	8,311	7,916
Non-cash provision for restructuring	1,083	3,191	1,137
Non-cash interest expense	8,987	8,951	9,620
Unrealized foreign currency transaction losses (gains)	(996)	7,336	(2,599)
Benefit from deferred taxes	113	(873)	(1,842)
Changes in operating assets and liabilities:
Accounts receivable	(6,689)	3,800	14,321
Inventories	(551)	12,280	(2,628)
Prepaid expenses and other current assets	5,832	(7,567)	(1,839)
Accounts payable	9,148	3,606	(18,959)
Accrued expenses, compensation and benefits and other liabilities	(8,853)	(8,189)	(6,280)
Income taxes payable	38	800	(9)
Deferred revenues	(9,135)	(31,152)	(122,617)
Net cash provided by (used in) operating activities	15,822	8,936	(49,195)
Cash flows from investing activities:
Purchases of property and equipment	(9,936)	(7,877)	(11,003)
Increase in other long-term assets	19	(36)	(30)
Net cash used in investing activities	(9,917)	(7,913)	(11,033)
Cash flows from financing activities:
Proceeds from long-term debt	22,688	16,694	100,000
Repayment of debt	(18,451)	(6,735)	(3,750)
Proceeds from issuance of common stock under employee stock plans	355	445	6,184
Common stock repurchases for tax withholdings for net settlement of equity awards	(998)	(1,329)	(941)
Proceeds from revolving credit facilities	0	0	25,000
Payments on revolving credit facilities	0	0	(30,000)
Repayments of Convertible Debt	(58)	0	0
Payments for credit facility issuance costs	(1,000)	(700)	(5,041)
Net cash provided by financing activities	2,536	8,375	91,452
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(780)	1,087	366
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	7,661	10,485	31,590
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	68,094	60,433	49,948
Supplemental information: [Abstract]
Cash and Cash Equivalents, at Carrying Value	56,103	57,223	44,948
Restricted Cash, Current	8,500	0	0
Restricted Cash, Noncurrent	3,491	3,210	5,000
Cash (refunded) paid for income taxes, net	(2,791)	(100)	1,587
Cash paid for interest	14,505	10,966	9,302
Non-cash transaction - property and equipment included in accounts payable or accruals	$ 220	$ 30	$ 119