Other Current Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Other current liabilities
Unrealized losses on foreign exchange contracts (Note 9)	$ 31.3	$ 15.6
Product warranty obligations (Note 7)	28.5	28.0	$ 27.9
Taxes other than income taxes	42.7	43.1
Accrued interest	16.9	16.9
Income taxes payable	32.6	28.6
Rocky Flats settlement (Note 18)		242.5
Other	68.2	72.9
Other current liabilities	$ 220.2	$ 447.6