CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018
Cash flows from operating activities:
Net loss	$ (23,151)	$ (16,607)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of intangibles	4,162	4,194
Depreciation	5,716	6,771
Stock-based compensation	4,623	8,769
Amortization of discount on convertible debt and issuance cost	3,262	2,954
Amortization of non-cash warrant	48	395
Restructuring, asset impairment and loss on retirement of fixed assets	101	93
Deferred income taxes, net	(145)	530
Foreign currency adjustments	(325)	(1,042)
Provision for excess and obsolete inventories	384	822
Allowance for doubtful accounts and returns	500	623
Other non-cash adjustments, net	303	64
Changes in operating assets and liabilities:
Accounts receivable	10,699	(13,572)
Inventories	(2,440)	2,000
Prepaid expenses and other assets	(1,526)	1,897
Accounts payable	(1,752)	(4,187)
Deferred revenue	4,989	9,378
Income taxes payable	(292)	503
Accrued and other liabilities	(9,802)	(337)
Net cash provided by (used in) operating activities	(4,646)	3,248
Cash flows from investing activities:
Purchases of property and equipment	(2,939)	(3,181)
Net cash used in investing activities	(2,939)	(3,181)
Cash flows from financing activities:
Proceeds from other debts and finance leases	4,503	0
Repayment of other debts and finance leases	(6,162)	(6,176)
Proceeds from common stock issued to employees	2,147	2,366
Payment of tax withholding obligations related to net share settlements of restricted stock units	(828)	(54)
Net cash used in financing activities	(340)	(3,864)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	(588)
Net increase (decrease) in cash, cash equivalents and restricted cash	(7,925)	(4,385)
Cash, cash equivalents and restricted cash at beginning of period	65,989	58,757
Cash, cash equivalents and restricted cash at end of period	58,064	54,372
Supplemental disclosures of cash flow information:
Income tax payments, net	860	750
Interest payments, net	2,495	2,545
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Capital expenditures incurred but not yet paid	78	491
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets
Total cash, cash equivalents and restricted cash	$ 65,989	$ 58,757