CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 177,285	$ 137,540
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	23,549	23,734
Share-based compensation	68,197	61,931
Deferred income taxes	(1,230)	247
Net (gain) loss on marketable securities	(998)	635
Amortization of Leased Asset	14,962	0
Provision for doubtful accounts, net	2,777	509
Net loss on sales of property and equipment	61	22
Changes in operating assets and liabilities:
Accounts receivable	(18,961)	(53,288)
Prepaid expenses and other assets	(9,734)	(5,369)
Accounts payable	(1,815)	631
Accrued compensation and employee benefits	(10,147)	4,217
Other liabilities	(12,330)	(6,164)
Deferred revenue	(2,886)	291
Net Cash Provided by (Used in) Operating Activities	228,730	164,936
Cash flows from investing activities:
Purchases of property and equipment	(21,073)	(18,170)
Proceeds from sales of marketable securities	3,462	3,228
Purchases of marketable securities	(5,790)	(5,858)
Distribution from other investments	55	0
Net Cash Provided by (Used in) Investing Activities	(23,346)	(20,800)
Cash flows from financing activities:
Proceeds from revolving line of credit	193,000	167,000
Payments on revolving line of credit	(435,000)	(109,000)
Proceeds from issuance of senior notes	350,000	0
Payments on debt issuance costs	(6,840)	0
Payment from finance lease	(811)	0
Proceeds from issuance of treasury stock under employee stock plans	26,235	16,073
Taxes paid related to net share settlement of equity awards	(100,067)	(51,208)
Repurchases of common stock	(210,000)	(178,926)
Net Cash Provided by (Used in) Financing Activities	(183,483)	(156,061)
Effect of exchange rate changes on cash	(2,654)	710
Increase (decrease) in cash and cash equivalents	19,247	(11,215)
Cash and cash equivalents, beginning of period	106,426	90,023
Cash and cash equivalents, end of period	125,673	78,808
Supplemental disclosures of cash flow information:
Cash paid for income taxes, net of refunds	5,723	12,058
Interest Paid, Excluding Capitalized Interest, Operating Activities	34,844	33,401
Supplemental disclosures of non-cash investing and financing activities:
Purchase of property and equipment included in accounts payable	50	690
Finance lease obligations incurred	$ 6,489	$ 6,416