CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (13,694)	$ (24,027)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of intangibles	2,099	2,069
Depreciation	3,456	3,599
Stock-based compensation	5,757	3,251
Amortization of discount on convertible debt and issuance cost	1,453	1,316
Restructuring, asset impairment and loss on retirement of fixed assets	40	187
Amortization of non-cash warrant	111	416
Foreign currency adjustments	835	182
Provision for excess and obsolete inventories	458	387
Allowance for doubtful accounts and returns	1,122	2,700
Other non-cash adjustments, net	132	72
Changes in operating assets and liabilities:
Accounts receivable	(5,925)	14,388
Inventories	424	942
Prepaid expenses and other assets	(6,511)	(3,151)
Accounts payable	(5,710)	(6,687)
Deferred revenue	10,009	5,435
Income taxes payable	253	6
Accrued and other liabilities	(933)	(4,181)
Net cash used in operating activities	(6,624)	(3,096)
Cash flows from investing activities:
Proceeds from maturities of investments	0	3,106
Proceeds from sales of investments	0	3,792
Purchases of property and equipment	(1,775)	(3,217)
Net cash (used in) provided by investing activities	(1,775)	3,681
Cash flows from financing activities:
Repayment of other debts and capital leases	(448)	(953)
Proceeds from common stock issued to employees	2,347	2,114
Payment of tax withholding obligations related to net share settlements of restricted stock units	0	(2,383)
Net cash provided by (used in) financing activities	1,899	(1,222)
Effect of exchange rate changes on cash and cash equivalents	73	347
Net decrease in cash, cash equivalents and restricted cash	(6,427)	(290)
Cash, cash equivalents and restricted cash at beginning of period	58,757	57,420
Cash, cash equivalents and restricted cash at end of period	$ 52,330	$ 57,130