Variable Interest Entities (World Energy) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2023 renewal	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
Variable Interest Entity [Line Items]
Financing receivables		$ 1,000.0	$ 1,220.2
Project exit costs		3,623.3	0.0	$ 217.6
World Energy, LLC | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Financing receivables			$ 300.0
Term of project agreement	15 years
Number of renewal terms of project agreement | renewal	2
Project agreement, renewal term (in years)	5 years
Project exit costs		1,900.0
Impairment of property and equipment		1,600.0
Provision for credit loss		$ 300.0