Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 19.7	$ 16.0	$ 37.8	$ 30.9
Land, buildings and improvements	812.0		812.0		$ 778.1
Less: Accumulated depreciation	307.5		307.5		274.2
Property, plant and equipment, net	504.5		504.5		503.9
Land, buildings and improvements
Property, Plant and Equipment [Line Items]
Land, buildings and improvements	154.8		154.8		146.6
Machinery, equipment and other
Property, Plant and Equipment [Line Items]
Land, buildings and improvements	$ 401.4		$ 401.4		$ 380.8