Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities
Net income	$ 285,018	$ 256,920
Adjustments to reconcile net income to net cash provided by operating activities:
Realized (gain) loss on disposition of assets and investments	(463)	22
Stock-based compensation	133,740	118,443
Provisions for doubtful accounts and sales returns	385	876
Depreciation and amortization	45,603	42,284
Deferred income taxes	(1,307)	9,295
Changes in operating assets and liabilities:
Accounts receivable	(27,295)	15,307
Inventories	3,007	(87)
Other current assets	1,063	(80)
Other assets	(425)	549
Accounts payable and accrued liabilities	14,270	(8,922)
Deferred revenue	73,620	72,858
Net cash provided by operating activities	527,216	507,465
Investing activities
Purchases of investments	(255,386)	(225,226)
Maturities of investments	271,878	244,905
Sales of investments	65,857	62,836
(Increase) decrease in restricted cash	(87)	29
Acquisition of intangible assets	(4,000)	(3,250)
Purchases of property and equipment	(31,175)	(45,909)
Net cash provided by investing activities	47,087	33,385
Financing activities
Excess tax benefit from stock-based compensation	6,471	1,596
Proceeds from the exercise of stock options and purchases of stock under employee stock purchase plan	46,959	44,848
Repurchase of common stock	(450,065)	(550,101)
Net cash used in financing activities	(396,635)	(503,657)
Net increase in cash and cash equivalents	177,668	37,193
Effect of exchange rate changes on cash and cash equivalents	(1,327)	1,944
Cash and cash equivalents, beginning of period	514,571	390,460
Cash and cash equivalents, end of period	$ 690,912	$ 429,597