CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Sep. 30, 2023		24,770
Beginning Balance at Sep. 30, 2023	$ (687,990)	$ 248	$ 1,350,713	$ (5,324,865)	$ 3,388,059	$ (102,145)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	31,574		31,574
Issuance of treasury stock under employee stock plans (in shares)		187
Issuance of treasury stock under employee stock plans	(127,413)	$ 2	(143,156)	15,741
Repurchases of common stock (in shares)		(78)
Repurchases of common stock	(71,704)	$ (1)		(71,703)
Net income	121,065				121,065
Foreign currency translation adjustments	8,703					8,703
Ending Balance (in shares) at Dec. 31, 2023		24,879
Ending Balance at Dec. 31, 2023	(725,765)	$ 249	1,239,131	(5,380,827)	3,509,124	(93,442)
Beginning Balance (in shares) at Sep. 30, 2024		24,392
Beginning Balance at Sep. 30, 2024	(962,679)	$ 244	1,366,572	(6,138,736)	3,900,870	(91,629)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	40,654		40,654
Issuance of treasury stock under employee stock plans (in shares)		130
Issuance of treasury stock under employee stock plans	(192,864)	$ 1	(205,398)	12,533
Repurchases of common stock (in shares)		(79)
Repurchases of common stock	(159,749)	$ (1)		(159,748)
Net income	152,528				152,528
Foreign currency translation adjustments	(16,054)					(16,054)
Ending Balance (in shares) at Dec. 31, 2024		24,443
Ending Balance at Dec. 31, 2024	$ (1,138,164)	$ 244	$ 1,201,828	$ (6,285,951)	$ 4,053,398	$ (107,683)