Other Current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
Other current liabilities
Unrealized losses on foreign exchange contracts	$ 16.1	$ 15.6
Product warranty obligations	26.6	28.0	$ 28.1	$ 27.9
Taxes other than income taxes	44.0	43.1
Accrued interest	16.9	16.9
Income taxes payable	49.6	28.6
Rocky Flats settlement (Note 14)	0.0	242.5
Other	61.7	72.9
Other current liabilities	$ 214.9	$ 447.6