Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Jun. 30, 2022
Numerator
Income from continuing operations	$ 64.5			$ 39.8			$ 124.4	$ 97.0
(Loss) income from discontinued operations	(2.9)			58.4			1,246.4	169.6
Net income	$ 61.6	$ 1,227.3	$ 81.9	$ 98.2	$ 81.4	$ 87.0	$ 1,370.8	$ 266.6
Denominator
Weighted-average common shares outstanding (shares)	161.5			178.6			169.5	179.6
Effect of potentially dilutive securities (shares)	1.0			1.2			1.1	1.3
Weighted average diluted shares outstanding (shares)	162.5			179.8			170.6	180.9
Basic earnings per share
Continuing operations, basic earnings per share (usd per share)	$ 0.40			$ 0.22			$ 0.74	$ 0.54
Discontinued operations, basic earnings per share (usd per share)	(0.02)			0.33			7.35	0.94
Basic earnings per share (usd per share)	0.38			0.55			8.09	1.48
Earnings Per Share, Diluted [Abstract]
Continuing operations, diluted earnings per share (usd per share)	0.40			0.22			0.73	0.53
Discontinued operations, diluted earnings per share (usd per share)	(0.02)			0.33			7.31	0.94
Diluted earnings per share (usd per share)	$ 0.38			$ 0.55			$ 8.04	$ 1.47
Shares excluded from diluted earnings per share calculation due to anti-dilutive effect (shares)	0.1			0.2			0.2	0.2