CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 373,541	$ 392,084	$ 236,411
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	20,465	25,592	30,367
Share-based compensation	115,355	112,457	93,681
Deferred income taxes	7,816	(5,955)	(8,639)
Non-cash operating lease costs	15,922	16,102	20,011
Impairment loss on operating lease assets	0	0	28,016
Provision of doubtful accounts	2,800	652	3,199
Net (gain) loss on marketable securities	9,269	(4,569)	(2,071)
Net loss on sales and abandonment of property and equipment	193	333	5,249
Gains on product line asset sales and business divestiture	0	(100,139)	0
Changes in operating assets and liabilities:
Accounts receivable	(31,557)	24,496	(59,889)
Prepaid expenses and other assets	7,368	(5,722)	(960)
Accounts payable	(2,802)	(2,354)	1,059
Accrued compensation and employee benefits	(3,637)	(13,144)	12,065
Other liabilities	(28,830)	(20,502)	693
Deferred revenue	23,547	4,486	5,724
Net cash provided by operating activities	509,450	423,817	364,916
Cash flows from investing activities:
Purchases of property and equipment	(6,029)	(7,569)	(21,989)
Proceeds from sales of marketable securities	8,063	7,237	3,470
Purchases of marketable securities	(9,963)	(9,039)	(6,119)
Proceeds from Sale of Productive Assets	2,258	147,431	0
Distribution from (purchase of) equity investment	0	(210)	55
Net cash provided by (used in) investing activities	(5,671)	137,850	(24,583)
Cash flows from financing activities:
Proceeds from revolving line of credit and term loan	1,039,000	682,000	263,000
Payments on revolving line of credit and term loan	(988,250)	(259,000)	(513,000)
Proceeds from issuance of senior notes	550,000	0	350,000
Payments on senior notes	0	0	(85,000)
Payments on debt issuance costs	(8,819)	(1,488)	(6,840)
Payments on finance leases	0	(176)	(1,716)
Proceeds from issuance of treasury stock under employee stock plans	16,026	20,881	42,258
Taxes paid related to net share settlement of equity awards	(50,942)	(91,609)	(102,903)
Repurchases of common stock	(1,104,180)	(874,179)	(235,223)
Net cash used in financing activities	(547,165)	(523,571)	(289,424)
Increase (decrease) in cash and cash equivalents	(62,152)	37,960	50,968
Cash and cash equivalents, beginning of year	195,354	157,394	106,426
Cash and cash equivalents, end of year	133,202	195,354	157,394
Supplemental disclosures of cash flow information:
Cash paid for income taxes, refunds	1,090	464	1,931
Income Taxes Paid, Net	65,332	71,486	10,152
Cash paid for interest	57,208	37,955	37,735
Supplemental disclosures of non-cash investing and financing activities:
Finance lease obligation incurred	0	0	1,387
Unsettled repurchases of common stock	0	8,043	0
Purchase of property and equipment included in accounts payable	22	71	166
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ (18,766)	$ (136)	$ 59