Consolidated Statements of Stockholder's Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Sep. 30, 2022	$ 2,296,034	$ 1,175	$ 1,720,580	$ 727,737	$ (153,458)
Beginning balance (in shares) at Sep. 30, 2022		117,472,000
Common stock issued for employee stock-based awards	0	$ 18	(18)
Common stock issued for employee stock-based awards (in shares)		1,798,000
Shares surrendered by employees to pay taxes related to stock-based awards	(82,768)	$ (7)	(82,761)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(620,000)
Common stock issued for employee stock purchase plan	21,652	$ 2	21,650
Common stock issued for employee stock purchase plan (in shares)		196,000
Compensation expense from stock-based awards	161,454		161,454
Net income	$ 245,540			245,540
Repurchases of common stock (in shares)	0
Loss on net investment hedges, net of tax	$ (7,516)				(7,516)
Foreign currency translation adjustment	45,692				45,692
Change in defined benefit pension items, net of tax	(2,798)				(2,798)
Ending balance at Sep. 30, 2023	2,677,290	$ 1,188	1,820,905	973,277	(118,080)
Ending balance (in shares) at Sep. 30, 2023		118,846,000
Common stock issued for employee stock-based awards	0	$ 18	(18)
Common stock issued for employee stock-based awards (in shares)		1,733,000
Shares surrendered by employees to pay taxes related to stock-based awards	(101,924)	$ (6)	(101,918)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(612,000)
Common stock issued for employee stock purchase plan	25,674	$ 2	25,672
Common stock issued for employee stock purchase plan (in shares)		188,000
Compensation expense from stock-based awards	220,666		220,666
Net income	$ 376,333			376,333
Repurchases of common stock (in shares)	0
Loss on net investment hedges, net of tax	$ (16,315)				(16,315)
Foreign currency translation adjustment	36,465				36,465
Change in defined benefit pension items, net of tax	(3,791)				(3,791)
Ending balance at Sep. 30, 2024	$ 3,214,398	$ 1,202	1,965,307	1,349,610	(101,721)
Ending balance (in shares) at Sep. 30, 2024	120,155,000	120,155,000
Common stock issued for employee stock-based awards	$ 0	$ 13	(13)
Common stock issued for employee stock-based awards (in shares)		1,300,000
Shares surrendered by employees to pay taxes related to stock-based awards	(80,355)	$ (5)	(80,350)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(439,000)
Common stock issued for employee stock purchase plan	26,062	$ 2	26,060
Common stock issued for employee stock purchase plan (in shares)		166,000
Compensation expense from stock-based awards	212,659		212,659
Net income	733,997			733,997
Repurchases of common stock	$ (301,090)	$ (17)	(301,073)
Repurchases of common stock (in shares)	(1,650,000)	(1,646,000)
Loss on net investment hedges, net of tax	$ (17,863)				(17,863)
Foreign currency translation adjustment	37,334				37,334
Change in defined benefit pension items, net of tax	1,087				1,087
Ending balance at Sep. 30, 2025	$ 3,826,229	$ 1,195	$ 1,822,590	$ 2,083,607	$ (81,163)
Ending balance (in shares) at Sep. 30, 2025	119,536,000	119,536,000