CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 144,020	$ 145,832	$ 64,295
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred taxes	(11,424)	4,088	(5,899)
Depreciation and amortization	18,004	17,856	16,825
Stock-based compensation	52,943	39,823	26,438
Tax (shortfalls) benefits from stock-based awards	10,224	21,393	27,103
Excess tax benefit from share-based payment arrangements	(10,396)	(21,393)	(27,103)
Impairment of goodwill	0	0	40,693
Impairment of long lived assets	0	0	26,320
Other	13,799	10,106	4,142
Changes in assets and liabilities, excluding the effects of business combinations:
Accounts receivable	(40,775)	(27,229)	(11,981)
Inventories	(3,563)	(1,999)	1,158
Prepaid expenses and other assets	(3,726)	(2,924)	(392)
Accounts payable	7,575	2,887	(186)
Accrued and other long-term liabilities	19,462	22,692	9,662
Deferred revenues	41,854	15,767	14,901
Net cash provided by operating activities	237,997	226,899	185,976
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition, net of cash acquired	0	0	(7,652)
Purchase of property, plant and equipment	(53,451)	(24,092)	(19,412)
Purchase of marketable securities	(447,092)	(437,152)	(303,917)
Proceeds from maturities of marketable securities	304,125	176,810	90,917
Proceeds from Sale and Maturity of Marketable Securities	30,011	82,990	31,741
Other assets	46	(183)	(2,411)
Net cash used in investing activities	(166,361)	(201,627)	(210,734)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	11,325	18,028	34,196
Common stock repurchase	(101,791)	(98,233)	(95,107)
Excess tax benefit from share-based payment arrangements	10,396	21,393	27,103
Employees' taxes paid upon the vesting of restricted stock units	(20,716)	(7,608)	(4,363)
Net cash used in financing activities	(100,786)	(66,420)	(38,171)
Effect of foreign exchange rate changes on cash and cash equivalents	(3,007)	(1,934)	(504)
Net decrease in cash and cash equivalents	(32,157)	(43,082)	(63,433)
Cash and cash equivalents, beginning of year	199,871	242,953
Cash and cash equivalents, end of year	$ 167,714	$ 199,871	$ 242,953