Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Service cost	$ 0.4	$ 0.4	$ 0.9	$ 0.9
Interest cost	5.4	5.4	10.7	10.6
Expected return on plan assets	(4.8)	(5.5)	(9.7)	(10.9)
Recognized net actuarial loss	0.3	0.4	0.7	0.8
Net periodic cost	$ 1.3	$ 7.9	$ 2.6	8.6
Defined benefit settlement loss				$ (7.2)