Income Taxes - Schedule of Income Tax Expense (Benefit) Differs from Amount Computed at Federal Statutory Corporate Tax Rate (Parenthetical) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Decrease in tax provision due to refund claims related to domestic production activities deduction	[1]		$ (1.7)
Decrease in tax provision due to revaluation of net deferred tax liability	[2]	$ 0.1	$ (43.4)

[1] In 2018, the Company calculated refund claims related to the domestic production activities deduction.  The refund claims reduced the tax provision by $1.7. The domestic production activities deduction was eliminated by the 2017 Tax Act.

[2] In 2018, the inclusion of the revaluation of the net deferred tax liability attributable to the 2017 Tax Act reduced the tax provision by $43.4.