CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 88,212	$ 77,344
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	27,427	23,127
Share-based compensation	43,546	41,704
Deferred income taxes	(2)	(455)
Tax effect from share-based payment arrangements	0	15,704
Provision for doubtful accounts, net	1,388	1,305
Net loss on sales of property and equipment	26	0
Changes in operating assets and liabilities:
Accounts receivable	25,605	(3,184)
Prepaid expenses and other assets	(26,171)	14,306
Accounts payable	(5,432)	(1,635)
Accrued compensation and employee benefits	(8,317)	2,556
Other liabilities	5,838	(1,166)
Deferred revenue	19,303	8,119
Net cash provided by operating activities	171,423	177,725
Cash flows from investing activities:
Purchases of property and equipment	(14,792)	(12,541)
Cash paid for acquisitions, net of cash acquired	0	(5,683)
(Purchase of) distribution from cost method investees	(777)	37
Net cash used in investing activities	(15,569)	(18,187)
Cash flows from financing activities:
Proceeds from revolving line of credit	98,000	49,000
Payments on revolving line of credit	(57,000)	(56,000)
Proceeds from issuance of treasury stock under employee stock plans	13,112	8,356
Taxes paid related to net share settlement of equity awards	(39,324)	(28,544)
Dividends paid	(1,238)	(1,869)
Repurchases of common stock	(116,341)	(96,121)
Net cash used in financing activities	(102,791)	(125,178)
Effect of exchange rate changes on cash	1,678	(2,325)
Increase in cash and cash equivalents	54,741	32,035
Cash and cash equivalents, beginning of period	75,926	86,120
Cash and cash equivalents, end of period	130,667	118,155
Supplemental disclosures of cash flow information:
Income taxes payments (refunds), net	22,726	(836)
Cash paid for interest	18,847	19,143
Supplemental disclosures of non-cash investing and financing activities:
Purchase of property and equipment included in accounts payable	2,470	3,566
Unsettled repurchases of common stock	$ 4,177	$ 4,351