Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 377,254	$ 283,224
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and other	25,235	21,170
Stock-based compensation	82,497	60,478
Noncash lease expense	8,410	8,223
Deferred income taxes	(2,998)	2,668
Amortization of investment premiums	12,121	2,938
Changes in operating assets and liabilities:
Accounts receivable, net	25,326	15,263
Inventories	(63,531)	(82,891)
Prepaid expenses and other current assets	(44,356)	26,815
Other assets	(3,390)	5,360
Accounts payable	10,879	31,473
Accrued liabilities	20,025	(39,882)
Deferred revenue	95,263	(19,242)
Income taxes payable	(9,144)	16,820
Other liabilities	(15,550)	646
Net cash provided by operating activities	518,041	333,063
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of marketable securities	819,807	875,213
Purchases of marketable securities	(1,241,657)	(1,236,477)
Purchases of property and equipment	(9,567)	(5,178)
Business acquisitions, net of cash acquired	0	(66,317)
Escrow receipts from past business acquisitions	1,419	0
Investment in privately-held companies and intangibles	(6,084)	0
Net cash used in investing activities	(436,082)	(432,759)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock under equity plans	26,884	22,228
Tax withholding paid on behalf of employees for net share settlement	(6,353)	(4,000)
Repurchase of common stock	(101,355)	(227,895)
Net cash used in financing activities	(80,824)	(209,667)
Effect of exchange rate changes	(665)	(1,663)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	470	(311,026)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH —Beginning of period	897,454	1,115,515
CASH, CASH EQUIVALENTS AND RESTRICTED CASH —End of period	897,924	804,489
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Right-of-use assets obtained in exchange for new operating lease liabilities	1,619	0
Property and equipment included in accounts payable and accrued liabilities	$ 1,732	$ 788