Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income		$ 423,201	$ 184,189	$ 121,102
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		20,640	19,749	13,671
Stock-based compensation		75,427	59,032	45,303
Deferred income taxes		8,426	(21,720)	(24,409)
Amortization of investment premiums		1,452	1,493	1,471
Changes in operating assets and liabilities:
Accounts receivable, net		5,773	(108,856)	(47,281)
Inventories		(69,708)	(144,361)	(14,123)
Prepaid expenses and other current assets		(11,645)	(115,074)	(7,827)
Other assets		907	2,866	(3,087)
Accounts payable		(30,104)	38,678	9,037
Accrued liabilities		43,535	30,629	20,398
Deferred revenue		142,327	176,126	90,340
Income taxes payable		19,921	42,650	32,018
Other liabilities		1,475	8,894	1,171
Net cash provided by operating activities	[1]	631,627	174,295	237,784
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of marketable securities		206,332	137,855	208,200
Purchases of marketable securities		(585,373)	(439,711)	0
Purchases of property and equipment		(15,279)	(21,419)	(19,989)
Proceeds from repayment of notes receivable		3,000	0	0
Investment in privately-held companies		0	(2,500)	0
Change in restricted cash		(1,260)	(204)	(4,041)
Net cash provided by (used in) investing activities		(392,580)	(325,979)	184,170
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments of lease financing obligations		(1,617)	(1,336)	(1,086)
Proceeds from issuance of common stock under equity plans		57,111	35,181	27,201
Minimum tax withholding paid on behalf of employees for net share settlement		(4,025)	(1,100)	0
Proceeds from initial public offering, net of issuance cost		0	0	(261)
Net cash provided by financing activities	[1]	51,469	32,745	25,854
Effect of exchange rate changes		753	(464)	(513)
NET INCREASE/(DECREASE) IN CASH AND CASH EQUIVALENTS		291,269	(119,403)	447,295
CASH AND CASH EQUIVALENTS—Beginning of year		567,923	687,326	240,031
CASH AND CASH EQUIVALENTS—End of year		859,192	567,923	687,326
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes, net of refunds		44,216	39,638	6,591
Cash paid for interest — lease financing obligation		2,814	2,916	2,999
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Property and equipment included in accounts payable and accrued liabilities		3,811	869	3,957
Vesting of early exercised stock options and restricted stock awards		$ 564	$ 1,082	$ 2,226

[1] During our first fiscal quarter of 2017, we adopted Accounting Standards Update 2016-09, "Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting." Refer to Note 1- Recently Adopted Accounting Pronouncements for further details. This adoption resulted in an increase in net cash provided by operating activities and a corresponding decrease in net cash provided by financing activities of $42.9 million and $37.3 million for the years ended December 31, 2016 and 2015, respectively.