Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Contingency [Line Items]
Provisional income tax expense (benefit)			$ 4.5
Income tax expense (benefit)	$ 4.6	$ 0.8	5.9	$ (1.9)
Pre-tax income (loss)	5.0	$ (0.3)	32.8	$ (11.3)
Valuation allowance	2.6		2.6			$ 3.1
Increase in uncertain tax positions related to acquisition			1.4
Interest and penalties	$ 1.5		1.5			$ 1.8
Reductions due to the statute of limitations expiration			$ (0.4)
Forecast
Income Tax Contingency [Line Items]
Federal income tax rate					24.30%