Income Taxes (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014
Income tax
Estimated effective income tax rate (as a percent)	10.00%	18.00%	18.00%
Income tax expense for discrete items in continuing operations	$ 0.9
Cumulative loss period			3 years
Net operating and capital loss carryforwards	77.8
Tax credit carryforwards	24.8
Unrecognized income tax benefits that may be released within next 12 months	$ 5.0
Minimum
Income tax
Carryover period for deferred tax attributes	20 years
Operating loss carryforwards expiration date	Sep. 30, 2015
Tax credit carryforwards, expiration date	Sep. 30, 2028
Maximum
Income tax
Operating loss carryforwards expiration date	Sep. 30, 2034
Tax credit carryforwards, expiration date	Sep. 30, 2034