Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013
Operating activities
Net loss	$ (15,957)	$ (1,656)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	3,596	3,104
Loss on disposal of property and equipment	592	0
Stock-based compensation	3,966	3,126
Imputed interest related to deposit arrangements, net	41	(60)
Amortization of premium and discount on investments, net	153	210
Cash received for lease incentives	0	135
Changes in operating assets and liabilities:
Accounts receivable	(1,183)	(6,780)
Inventories	13,558	(3,191)
Prepaids and other current and noncurrent assets	(1,760)	4,236
Accounts payable and accrued liabilities	(338)	(11,107)
Customer deposits	0	(11,425)
Deferred revenue	4,111	(4,884)
Net cash provided by (used in) operating activities	6,779	(28,292)
Investing activities
Purchase of property and equipment	(891)	(3,900)
Purchase of marketable securities	(18,153)	(8,882)
Sale and maturity of marketable securities	16,040	19,718
Net cash provided by (used in) investing activities	(3,004)	6,936
Financing activities
Payments on obligations under capital leases	0	(12)
Payments on customer deposit financing arrangement	(916)	(4,881)
Proceeds from exercise of stock options	805	734
Payments related to net share settlement of equity awards	(134)	0
Net cash used in financing activities	(245)	(4,159)
Effect of exchange rate changes on cash and cash equivalents	(49)	(1)
Net change in cash and cash equivalents	3,481	(25,516)
Cash and cash equivalents at beginning of period	16,249	44,106
Cash and cash equivalents at end of period	19,730	18,590
Supplemental disclosure of non cash financing activities
Capital lease obligation for capital equipment	0	17
Reclassification of restricted stock to equity upon vesting of early exercised options	$ 0	$ 4