Condensed Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net income	$ 474,700	$ 409,949
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and other	188,443	161,582
Stock-based compensation expense	202,523	144,306
Deferred income tax (benefit) expense	(184,573)	2,508
Effects of exchange rate changes on monetary assets and liabilities denominated in foreign currencies	2,712	7,226
Other non-cash items	7,888	5,558
Total adjustments to reconcile net income to net cash provided by operating activities	216,993	321,180
Changes in operating assets and liabilities, net of the effects of acquisitions:
Accounts receivable	256,628	296,286
Inventories	443	(7,549)
Prepaid expenses and other current assets	(13,539)	(51,726)
Other assets	(50,068)	(17,540)
Income taxes, net	(42,119)	(83,273)
Accounts payable	(2,645)	2,945
Accrued expenses and other current liabilities	(48,485)	40,503
Deferred revenues	(219,000)	(85,072)
Other liabilities	4,111	3,233
Total changes in operating assets and liabilities, net of the effects of acquisitions	(114,674)	97,807
Net cash provided by operating activities	577,019	828,936
Investing Activities
Purchases of available-for-sale investments	(19,999)	(435,876)
Proceeds from sales of available-for-sale investments	938,031	442,360
Proceeds from maturities of available-for-sale investments	165,944	320,259
Purchases of property and equipment	(50,453)	(54,289)
Cash paid for acquisitions, net of cash acquired	0	(65,983)
Cash paid for licensing agreements, patents and technology	(2,405)	(2,140)
Other	919	1,399
Net cash provided by investing activities	1,032,037	205,730
Financing Activities
Proceeds from issuance of common stock under stock-based compensation plans	0	164
Proceeds from credit facility	200,000	0
Repayment of credit facility	(200,000)	0
Repayment of acquired debt	0	(5,674)
Repayment on convertible notes	(1,164,497)	0
Stock repurchases, net	(353,904)	(881,153)
Cash paid for tax withholding on vested stock awards	(74,794)	(53,589)
Cash paid for dividends	(137,224)	0
Net cash used in financing activities	(1,730,419)	(940,252)
Effect of exchange rate changes on cash and cash equivalents	(3,569)	(4,362)
Change in cash and cash equivalents	(124,932)	90,052
Cash and cash equivalents at beginning of period	$ 618,766	$ 1,115,130