Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 4,806	$ 2,406
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,518	2,479
Stock-based compensation	6,831	2,600
Loss on disposal of assets	121	18
Changes in operating assets and liabilities:
Accounts receivable	(3,757)	(1,132)
Inventories	(5,649)	(2,512)
Prepaid expenses and other assets	(1,517)	(1,254)
Accounts payable	2,497	(5,051)
Accrued expenses and other liabilities	6,031	2,946
Deferred revenue	24,390	3,503
Net cash provided by operating activities	39,271	4,003
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(37,537)	(8,243)
Purchases of short-term and other investments	(59,996)	(18,000)
Proceeds from maturity and sale of short-term and other investments	25,000	8,000
Purchases of restricted cash	0	(3,600)
Proceeds from maturity of restricted cash	0	3,681
Net cash used in investing activities	(72,533)	(18,162)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	1,526	158
Payments of deferred offering costs	(385)	0
Debt issuance costs	(409)	0
Net cash provided by financing activities	732	158
Effect of exchange rate changes on cash and cash equivalents	(2)	18
NET DECREASE IN CASH AND CASH EQUIVALENTS	(32,532)	(13,983)
CASH AND CASH EQUIVALENTS—Beginning of period	290,089	96,998
CASH AND CASH EQUIVALENTS—End of period	257,557	83,015
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Payable for capital purchases	(1,851)	(255)
Stock-based compensation capitalized	16	7
Deferred Debt Issuance Costs	3	0
Deferred Debt Issuance Costs	4	4
Deferred initial public offering cost accruals	0	361
Accretion of redeemable convertible preferred stock	$ 0	$ 5,062