Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 74,149	$ 48,488
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,662	6,246
Stock-based compensation	27,592	20,047
Deferred income taxes	(6,876)	(2,266)
Excess tax benefit on stock-based compensation	(15,967)	(22,975)
Amortization of investment premiums	385	883
Changes in operating assets and liabilities:
Accounts receivable	(2,396)	(25,360)
Inventories	(26,001)	(22,297)
Prepaid expenses and other current assets	(2,838)	(20,747)
Other assets	1,866	(3,257)
Accounts payable	18,501	11,822
Accrued liabilities	(5,196)	3,082
Deferred revenue	33,516	57,975
Income taxes payable	17,853	21,846
Other liabilities	1,779	(114)
Net cash provided by operating activities	126,029	73,373
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(292,938)	0
Purchases of property and equipment	(12,042)	(8,768)
Purchases of intangible assets	(697)	(705)
Investment in privately-held companies	(2,500)	0
Net cash used in investing activities	(308,177)	(9,473)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments of lease financing obligations	(634)	(514)
Proceeds from issuance of common stock upon exercising options, net of repurchases	6,317	11,991
Minimum tax withholding paid on behalf of employees for net share settlement	(599)	0
Proceeds from issuance of common stock under employee stock purchase plan	4,888	4,856
Excess tax benefit on stock-based compensation	15,967	22,975
Issuance costs from initial public offering	0	(261)
Net cash provided by financing activities	25,939	39,047
Effect of exchange rate changes	(59)	(20)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(156,268)	102,927
CASH AND CASH EQUIVALENTS—Beginning of period	687,326	240,031
CASH AND CASH EQUIVALENTS—End of period	531,058	342,958
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes, net of refunds	18,584	3,501
Cash paid for interest—lease financing obligation	1,469	1,509
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Property and equipment included in accounts payable and accrued liabilities	$ 1,408	$ 619