Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit), including discontinued operations	$ 4.3		$ 5.7	$ 113.2	$ (1.3)
Tax credit			$ 1.3	$ 2.8
Corporate Tax Rate per The Tax Cuts and Jobs Acts (TTCJA) [Line Items]
Provisional tax expense per the Tax Cuts Cuts and Jobs Act		$ 112.6
Maximum
Corporate Tax Rate per The Tax Cuts and Jobs Acts (TTCJA) [Line Items]
Corporate Tax Rate per The Tax Cuts and Jobs Acts (TTCJA)	35.00%			35.00%
Minimum
Corporate Tax Rate per The Tax Cuts and Jobs Acts (TTCJA) [Line Items]
Corporate Tax Rate per The Tax Cuts and Jobs Acts (TTCJA)	21.00%			21.00%