Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 21, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 8.8	$ 11.8
Income tax expense as a percent of pre-tax income (loss)	21.80%	33.50%
Tax Cuts and Jobs Act of 2017, tax expense for transition tax			$ 5.0
Tax Cuts and Jobs Act, provisional net benefit for re-measurement of deferred tax assets and liabilities			$ 74.6
Indefinitely reinvested foreign earnings				$ 93.8