CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 138,599	$ 90,694
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	6,145	(8,608)
Depreciation and amortization	16,743	9,885
Stock-based compensation	29,057	26,223
Net tax benefits from stock-based awards	0	9,811
Excess tax benefit from share-based payment arrangements	0	(10,697)
Equity in losses of investee	3,336	0
Other non-cash operating activities	5,837	7,041
Changes in assets and liabilities, net of effects of acquisitions:
Accounts receivable	(52,038)	(38,433)
Inventories	(8,616)	(3,524)
Prepaid expenses and other assets	388	(5,025)
Accounts payable	4,410	(4,753)
Accrued and other long-term liabilities	(15,353)	4,446
Deferred revenues	29,580	29,787
Net cash provided by operating activities	158,088	106,847
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	(8,953)	0
Purchase of property, plant and equipment	(78,045)	(39,025)
Purchase of marketable securities	(212,226)	(241,364)
Proceeds from maturities of marketable securities	173,094	210,693
Proceeds from sales of marketable securities	32,352	24,224
Loan advance to equity investee	(15,000)	0
Other investing activities	224	(6,031)
Net cash used in investing activities	(108,554)	(51,503)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	7,521	7,002
Common stock repurchases	(38,793)	(35,000)
Equity forward contract related to accelerated share repurchase	(15,000)	(15,000)
Excess tax benefit from share-based payment arrangements	0	10,697
Employees’ taxes paid upon the vesting of restricted stock units	(37,968)	(23,207)
Net cash used in financing activities	(84,240)	(55,508)
Effect of foreign exchange rate changes on cash and cash equivalents	3,613	156
Net decrease in cash and cash equivalents	(31,093)	(8)
Cash and cash equivalents, end of the period	389,275	167,714
Cash and cash equivalents, end of the period	358,182	167,706
SUPPLEMENTAL CASH FLOW INFORMATION:
Accounts payable or accrued liabilities related to property, plant and equipment	$ 20,291	$ 10,009