CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 321,514	$ 302,843
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	1,470	2,047
Depreciation and amortization	57,194	38,185
Non-cash operating lease cost	13,600
Impairments on long-lived assets	28,498	0
Gain on lease terminations	(6,792)
Impairment on equity investment	3,975	0
Gain from sale of equity method investment	(15,769)	0
Stock-based compensation	67,687	51,918
Equity in losses of investee	7,528	6,610
Other non-cash operating activities	17,426	11,363
Changes in assets and liabilities:
Accounts receivable	(95,566)	(89,843)
Inventories	(40,775)	(17,192)
Prepaid expenses and other assets	(14,826)	(47,775)
Accounts payable	1,343	5,042
Accrued and other long-term liabilities	31,089	(25,436)
Long-term income tax payable	13,425	(18,435)
Deferred revenues	138,072	94,059
Net cash provided by operating activities	529,093	313,386
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(107,157)	(169,033)
Purchase of marketable securities	(588,805)	(150,022)
Proceeds from maturities of marketable securities	211,829	259,870
Proceeds from sales of marketable securities	194,677	9,560
Purchase of investments in privately held companies	0	(5,000)
Note repayment from privately held company	13,185	0
Loan repayment from equity investee	0	30,000
Other investing activities	(14,062)	604
Net cash used in investing activities	(290,333)	(24,021)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	17,907	16,607
Common stock repurchases	(299,504)	(250,002)
Employees’ taxes paid upon the vesting of restricted stock units	(55,793)	(81,756)
Purchase of finance lease	(45,773)	0
Net cash used in financing activities	(383,163)	(315,151)
Effect of foreign exchange rate changes on cash, cash equivalents, and restricted cash	(2,098)	(2,890)
Net decrease in cash, cash equivalents, and restricted cash	(146,501)	(28,676)
Cash, cash equivalents, and restricted cash at beginning of the period	637,566	450,125
Cash, cash equivalents, and restricted cash at end of the period	$ 491,065	$ 421,449