CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ DEFICIT (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Stockholders' Deficit, beginning of period at Sep. 30, 2024		$ 1.4	$ 37.3	$ 56.4	$ (2.0)	$ (299.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity under stock and deferred compensation plans			(11.1)
Non-cash stock-based compensation expense			11.7
Net earnings	$ 135.6			135.6
Foreign currency translation adjustments					(0.7)
Purchases of treasury stock	(183.7)					(183.7)
Stockholders' Deficit, end of period at Mar. 31, 2025	(254.1)	1.4	37.9	192.0	(2.7)	(482.7)
Stockholders' Deficit, beginning of period at Dec. 31, 2024		1.4	32.1	133.3	(3.4)	(310.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity under stock and deferred compensation plans			0.2
Non-cash stock-based compensation expense			5.6
Net earnings	58.7			58.7
Foreign currency translation adjustments					0.7
Purchases of treasury stock	(172.7)					(172.7)
Stockholders' Deficit, end of period at Mar. 31, 2025	(254.1)	1.4	37.9	192.0	(2.7)	(482.7)
Stockholders' Deficit, beginning of period at Sep. 30, 2025	(453.9)	1.4	48.7	272.6	(1.0)	(775.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity under stock and deferred compensation plans			(7.9)
Non-cash stock-based compensation expense			11.2
Net earnings	77.6			77.6
Foreign currency translation adjustments					(0.4)
Purchases of treasury stock	(124.4)					(124.4)
Stockholders' Deficit, end of period at Mar. 31, 2026	(497.8)	1.4	52.0	350.2	(1.4)	(900.0)
Stockholders' Deficit, beginning of period at Dec. 31, 2025		1.4	46.0	316.3	(1.0)	(873.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Activity under stock and deferred compensation plans			0.2
Non-cash stock-based compensation expense			5.8
Net earnings	33.9			33.9
Foreign currency translation adjustments					(0.4)
Purchases of treasury stock	(26.6)					(26.6)
Stockholders' Deficit, end of period at Mar. 31, 2026	$ (497.8)	$ 1.4	$ 52.0	$ 350.2	$ (1.4)	$ (900.0)