Commitments and Contingencies (Pace, Piedmont and Pasadena - Narrative) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2012 USD ($) surfaceImpoundmentUnit	Sep. 30, 2008 USD ($)	Sep. 30, 2006 USD ($)
Environmental
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 87.4	$ 79.1
Accrual for environmental loss contingencies, maximum payout period	30 years
Pace, Florida
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 54.4					$ 42.0
Change in estimated exposure		19.0	$ 19.0
Pace, Florida | Environmental
Loss Contingencies [Line Items]
Site Contingency, Cost Review, Period	5 years
Accrual for environmental loss contingencies, maximum payout period	30 years
Pace, Florida | Discontinued operations
Loss Contingencies [Line Items]
Pretax environmental expense		$ 19.0	$ 19.0			$ 42.0
Piedmont, South Carolina
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 10.5				$ 24.0
Change in estimated exposure	9.0
Piedmont, South Carolina | Discontinued operations
Loss Contingencies [Line Items]
Pretax environmental expense	9.0				$ 24.0
Pasadena, Texas
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 10.0
Number of closed facilities | surfaceImpoundmentUnit				2
Total anticipated exposure				$ 13.0