Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Foreign Currency Translation Adjustments	Treasury Stock, Common
Stockholders' Equity at Sep. 30, 2022		$ 0.0	$ 1.4	$ 7.0	$ (355.6)	$ (4.3)	$ (24.7)
Preferred stock, shares at Sep. 30, 2022		0.0
Common stock, shares at Sep. 30, 2022			135.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments						1.2
Purchases of treasury stock, shares			(4.2)
Purchases of treasury stock							(126.3)
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture			0.1
Activity under deferred compensation plans				(1.9)
Stock-based compensation expense				14.2
Net Earnings	$ 165.5				165.5
Stockholders' Equity at Sep. 30, 2023	(323.5)	$ 0.0	$ 1.4	19.3	(190.1)	(3.1)	(151.0)
Preferred stock, shares at Sep. 30, 2023		0.0
Common stock, shares at Sep. 30, 2023			131.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments						1.1
Purchases of treasury stock, shares			(2.6)
Purchases of treasury stock							(148.0)
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture			0.2
Activity under deferred compensation plans				(3.0)
Stock-based compensation expense				21.0
Net Earnings	246.5				246.5
Stockholders' Equity at Sep. 30, 2024	(205.9)	$ 0.0	$ 1.4	37.3	56.4	(2.0)	(299.0)
Preferred stock, shares at Sep. 30, 2024		0.0
Common stock, shares at Sep. 30, 2024			128.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments						1.0
Purchases of treasury stock, shares			(9.0)
Purchases of treasury stock							(476.6)
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture			1.0
Activity under deferred compensation plans				(10.7)
Stock-based compensation expense				22.1
Net Earnings	216.2				216.2
Stockholders' Equity at Sep. 30, 2025	$ (453.9)	$ 0.0		$ 48.7	$ 272.6	$ (1.0)	$ (775.6)
Preferred stock, shares at Sep. 30, 2025		0.0
Common stock, shares at Sep. 30, 2025			120.8