Income Taxes (Schedule of Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Current:
United States - Federal	$ 4.7	$ 13.5	$ 1.2
State	1.6	3.0	3.0
Foreign	49.9	39.2	37.5
Total current	56.2	55.7	41.7
Deferred:
United States - Federal	(57.8)	(29.4)	(22.1)
State	(3.8)	(3.1)	(4.1)
Foreign	(1.3)	(2.3)	(7.1)
Total deferred	(62.9)	(34.8)	(33.3)
(Benefit)/provision for income taxes	$ (6.7)	$ 20.9	$ 8.4