Income Taxes (Schedule of Components of Income before Income Taxes and the Consolidated Income Tax Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income before income taxes:
Domestic	$ 129.0	$ 92.2	$ 49.2
Foreign	54.0	46.1	15.9
Total	183.0	138.3	65.1
Current provision
Federal	61.6	4.7	35.3
State	8.6	2.2	3.6
Foreign	13.3	9.1	1.7
Total current provision	83.5	16.0	40.6
Deferred provision:
Federal	(34.9)	21.8	(18.1)
State	1.3	1.2	(1.3)
Foreign	0.8	(23.5)	(2.9)
Total deferred provision	(32.8)	(0.5)	(22.3)
Income tax expense	$ 50.7	$ 15.5	$ 18.3