Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (2,237)	$ 2,971
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	2,021	1,271
Stock-based compensation expense	12,554	8,176
Deferred income taxes	(4,137)	(117)
Inventory write-down	206	175
Other	29	25
Changes in operating assets and liabilities:
Accounts receivable	18,996	2,263
Inventories	(770)	(2,073)
Prepaid expenses and other assets	(2,792)	654
Accounts payable	1,718	(254)
Accrued liabilities and other liabilities	(14,371)	(13,076)
Deferred revenue	(1,947)	(3,282)
Net cash provided by (used in) operating activities	9,270	(3,267)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of short-term investments	(33,710)	(29,107)
Proceeds from maturities of short-term investments	37,500	26,786
Purchase of property and equipment	(2,695)	(2,107)
Net cash provided by (used in) investing activities	1,095	(4,428)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from employee stock purchase plan	4,956	3,368
Proceeds from exercise of stock options	581	1,377
Shares repurchased for tax withholdings on vesting of restricted stock units	(4,339)	(1,385)
Net cash provided by financing activities	1,198	3,360
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	11,563	(4,335)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	148,926	120,212
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	160,489	115,877
Current assets - Cash and cash equivalents	159,676	115,877
Other assets, non-current - restricted cash	813	0
Cash and cash equivalents	159,676	115,877
Income taxes paid during the period	750	283
Unpaid property and equipment purchases	$ 955	$ 314