Supplemental Information (Changes in Estimates) (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ 643.6	$ 666.9
Contracts accounted for under percentage of completion
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ 28.0	$ 30.0

The net result for the period of deducting operating expenses from operating revenues.

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