Supplemental Information (Other Noncurrent Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Disclosure Text Block Supplement [Abstract]
World Energy deferred project costs	$ 329.4	$ 202.9
Pension benefits	200.0	120.0
Deferred tax assets	127.8	159.6
Prepaid tax	41.0	22.2
Investments other than equity method	67.1	66.9
Deferred financing fees	4.6	58.8
Derivative instruments	48.7	320.6
Other	352.9	278.9
Other noncurrent assets	$ 1,171.5	$ 1,229.9