Consolidated Statements of Stockholder's Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Sep. 30, 2024	$ 3,214,398	$ 1,202	$ 1,965,307	$ 1,349,610	$ (101,721)
Beginning balance (in shares) at Sep. 30, 2024		120,155,000
Common stock issued for employee stock-based awards	0	$ 7	(7)
Common stock issued for employee stock-based awards (in shares)		695,000
Shares surrendered by employees to pay taxes related to stock-based awards	(47,193)	$ (3)	(47,190)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(248,000)
Compensation expense from stock-based awards	93,297		93,297
Repurchases of common stock, including excise tax	(75,000)	$ (4)	(74,996)
Repurchases of common stock, including excise tax		(383,000)
Net Income (Loss)	82,232			82,232
Gain (Loss) on net investment hedges, net of tax	25,240				25,240
Foreign currency translation adjustment	(63,997)				(63,997)
Change in defined benefit pension items, net of tax	844				844
Ending balance at Dec. 31, 2024	3,229,821	$ 1,202	1,936,411	1,431,842	(139,634)
Ending balance (in shares) at Dec. 31, 2024		120,219,000
Beginning balance at Sep. 30, 2025	$ 3,826,229	$ 1,195	1,822,590	2,083,607	(81,163)
Beginning balance (in shares) at Sep. 30, 2025	119,536,000	119,536,000
Common stock issued for employee stock-based awards	$ 0	$ 8	(8)
Common stock issued for employee stock-based awards (in shares)		781,000
Shares surrendered by employees to pay taxes related to stock-based awards	(49,831)	$ (3)	(49,828)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(283,000)
Compensation expense from stock-based awards	100,648		100,648
Repurchases of common stock, including excise tax	(201,161)	$ (11)	(201,150)
Repurchases of common stock, including excise tax		(1,142,000)
Net Income (Loss)	166,518			166,518
Gain (Loss) on net investment hedges, net of tax	(589)				(589)
Foreign currency translation adjustment	529				529
Change in defined benefit pension items, net of tax	76				76
Ending balance at Dec. 31, 2025	$ 3,842,419	$ 1,189	$ 1,672,252	$ 2,250,125	$ (81,147)
Ending balance (in shares) at Dec. 31, 2025	118,892,000	118,892,000