Revenue Recognition (Contract Assets and Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Contract assets – current	$ 152.6	$ 76.2
Contract fulfillment costs – current	85.4	103.7
Contract assets – noncurrent	82.3	0.0
Contract fulfillment costs – noncurrent	33.8	0.0
Contract liabilities – current	253.4	240.0
Contract liabilities – noncurrent	283.6	$ 290.0
Revenue recognized that was previously included in current contract liabilities	$ 110.0