CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 95,866	$ 69,420
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	4,069	7,789
Depreciation and amortization	11,434	7,867
Stock-based compensation	15,830	14,812
Equity in losses of investee	1,777	1,121
Other non-cash operating activities	474	2,079
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	(36,026)	(24,525)
Inventories	(4,002)	(7,923)
Prepaid expenses and other assets	(15,873)	(527)
Accounts payable	5,599	5,522
Accrued and other long-term liabilities	(35,466)	(40,891)
Long-term income tax payable	5,259	1,189
Deferred revenues	28,391	11,688
Net cash provided by operating activities	77,332	47,621
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	0	(8,953)
Purchase of property, plant and equipment	(57,578)	(59,569)
Purchase of marketable securities	0	(169,777)
Proceeds from maturities of marketable securities	126,825	87,003
Proceeds from sales of marketable securities	9,560	11,684
Loan advances to equity investee	0	(8,000)
Loan repayment from equity investee	30,000	0
Other investing activities	462	(850)
Net cash provided by (used in) investing activities	109,269	(148,462)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	8,020	7,288
Common stock repurchases	(100,000)	(3,793)
Employees’ taxes paid upon the vesting of restricted stock units	(47,842)	(36,496)
Net cash used in financing activities	(139,822)	(33,001)
Effect of foreign exchange rate changes on cash and cash equivalents, and restricted cash	1,715	2,430
Net increase (decrease) in cash, cash equivalents, and restricted cash	48,494	(131,412)
Cash, cash equivalents, and restricted cash at beginning of the period	450,125	393,019
Cash, cash equivalents, and restricted cash at end of the period	498,619	261,607
SUPPLEMENTAL CASH FLOW INFORMATION:
Accounts payable or accrued liabilities related to property, plant and equipment	$ 18,739	$ 7,662