Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Income tax
Estimated effective income tax rate (as a percent)			39.00%	10.00%	10.00%
Net operating and capital loss carryforwards	$ 59.8		$ 59.8
Tax credit carryforwards	25.0		$ 25.0
Income tax benefit for discrete items	$ 3.0	$ 0.9
Minimum
Income tax
Operating loss carryforwards expiration date			Sep. 30, 2016
Tax credit carryforwards, expiration date			Sep. 30, 2028
Maximum
Income tax
Operating loss carryforwards expiration date			Sep. 30, 2035
Tax credit carryforwards, expiration date			Sep. 30, 2033