CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net income	$ 651,946	$ 512,811	$ 429,375
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,952	13,827	14,638
Share-based compensation	156,667	149,439	123,847
Deferred income taxes	(32,486)	(27,330)	(47,378)
Net gain on marketable securities	(5,024)	(9,834)	(2,908)
Non-cash operating lease costs	9,604	12,423	14,708
Provision of doubtful accounts	1,485	1,675	1,475
Gain on product line asset sale	0	0	(1,941)
Net loss on sales and abandonment of property and equipment	210	438	547
Changes in operating assets and liabilities:
Accounts receivable	(100,377)	(34,144)	(70,117)
Prepaid expenses and other assets	610	(14,034)	(11,904)
Accounts payable	9,849	3,316	2,236
Accrued compensation and employee benefits	10,065	3,195	4,631
Other liabilities	31,566	7,216	(7,057)
Deferred revenue	29,740	13,966	18,763
Net cash provided by operating activities	778,807	632,964	468,915
Cash flows from investing activities:
Purchases of property and equipment	(8,922)	(8,884)	(4,237)
Capitalized internal-use software costs	(30,485)	(16,667)	0
Proceeds from sales of marketable securities	2,184	15,930	5,032
Purchases of marketable securities	(6,496)	(18,372)	(10,623)
Cash transferred, net of proceeds, from product line asset sale	0	0	(6,126)
Net cash used in investing activities	(43,719)	(27,993)	(15,954)
Cash flows from financing activities:
Proceeds from revolving line of credit and term loans	725,000	947,000	407,000
Payments on revolving line of credit and term loans	(1,368,750)	(602,000)	(402,000)
Proceeds from issuance of senior notes	1,500,000	0	0
Payments on debt issuance costs	(17,163)	(706)	0
Payments on finance leases	(3,144)	(1,333)	0
Proceeds from issuance of treasury stock under employee stock plans	32,823	25,006	22,198
Taxes paid related to net share settlement of equity awards	(204,593)	(139,188)	(76,673)
Repurchases of common stock	(1,414,502)	(821,702)	(405,526)
Net cash used in financing activities	(750,329)	(592,923)	(455,001)
Effect of exchange rate changes on cash	(1,290)	1,841	5,616
Increase (decrease) in cash and cash equivalents	(16,531)	13,889	3,576
Cash and cash equivalents, beginning of year	150,667	136,778	133,202
Cash and cash equivalents, end of year	134,136	150,667	136,778
Supplemental disclosures of cash flow information:
Cash paid for income taxes, net of refunds of $8,649, $859 and $640 during the years ended September 30, 2025, 2024 and 2023, respectively	162,089	133,716	152,775
Cash paid for interest	103,564	106,388	96,877
Supplemental disclosures of non-cash investing and financing activities:
Unsettled repurchases of common stock	18,416	13,391	1,821
Purchase of property and equipment included in accounts payable	47	62	106
Finance lease obligation incurred	$ 0	$ 11,740	$ 0