Supplemental Information (Other Income Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Other Income (Expense) [Abstract]
Technology and royalty income	$ 20.1	$ 25.0	$ 26.8
Interest income	6.2	4.6	9.4
Foreign exchange	(5.8)	(22.3)	(7.7)
Sale of assets and investments	10.1	37.1	12.5
Contract settlements	12.6	0.0	2.8
Other	14.9	2.9	9.0
Total Other Income (Expense), net	$ 58.1	$ 47.3	$ 52.8