Supplemental Information (Changes in Estimates) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ 644.2	$ 627.4	$ 1,756.0	$ 1,712.3
Contracts accounted for under percentage of completion
Change in Accounting Estimate [Line Items]
Operating income (loss)	$ (45.0)		$ (105.0)	$ (30.0)