EARNINGS PER SHARE - Schedule of Earnings Per Share Computation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Earnings Per Share, Diluted, by Common Class, Including Two Class Method
Net earnings	$ 33.9	$ 58.7	$ 77.6	$ 135.6
Weighted-average shares for basic earnings per share (in shares)	117.3	128.2	118.3	128.5
Weighted-average shares for diluted earnings per share (in shares)	117.5	129.9	118.7	130.5
Basic earnings per common share (in USD per share)	$ 0.29	$ 0.46	$ 0.66	$ 1.06
Diluted earnings per common share (in USD per share)	$ 0.29	$ 0.45	$ 0.65	$ 1.04
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method
Effect of dilutive securities (in shares)	0.0	0.2	0.1	0.2
Restricted stock units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method
Effect of dilutive securities (in shares)	0.2	0.3	0.2	0.3
Performance-based restricted stock units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method
Effect of dilutive securities (in shares)	0.0	1.2	0.1	1.5