CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ (12,674)	$ 42,998
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	16,932	19,169
(Recovery) provision for doubtful accounts	(158)	890
Stock-based compensation expense	5,874	6,116
Non-cash provision for restructuring	3,191	1,137
Non-cash interest expense	7,255	7,935
Unrealized foreign currency transaction losses	6,885	2,021
Benefit for deferred taxes	(925)	(5,187)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	2,877	17,057
Inventories	9,542	(7,561)
Prepaid expenses and other current assets	(3,958)	(1,493)
Accounts payable	2,065	(19,627)
Accrued expenses, compensation and benefits and other liabilities	543	(4,384)
Income taxes payable	(161)	347
Deferred revenues	(31,185)	(108,343)
Net cash provided by (used in) operating activities	6,103	(48,925)
Cash flows from investing activities:
Purchases of property and equipment	(6,125)	(9,681)
Increase in other long-term assets	(24)	(17)
Decrease (increase) in restricted cash	1,790	(4,544)
Net cash used in investing activities	(4,359)	(14,242)
Cash flows from financing activities:
Proceeds from long-term debt	912	100,000
Repayment of debt	(3,750)	(2,500)
Proceeds from the issuance of common stock under employee stock plans	219	5,914
Common stock repurchases for tax withholdings for net settlement of equity awards	(732)	(803)
Proceeds from revolving credit facilities	0	25,000
Payments on revolving credit facilities	0	(30,000)
Payments for credit facility issuance costs	0	(5,020)
Net cash (used in) provided by financing activities	(3,351)	92,591
Effect of exchange rate changes on cash and cash equivalents	753	391
Net (decrease) increase in cash and cash equivalents	(854)	29,815
Cash and cash equivalents at beginning of period	44,948	17,902
Cash and cash equivalents at end of period	44,094	47,717
Supplemental Cash Flow Information [Abstract]
Cash paid for income taxes, net of refunds	463	1,678
Cash paid for interest	$ 7,406	$ 5,767