Supplemental Information (Changes in Estimates) (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ 734.5	$ 643.6
Contracts accounted for under percentage of completion
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ (33.0)	$ (28.0)

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

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+ Details