Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014
Income Taxes
Effective tax rate (as a percent)	6.00%		22.00%
Additional income tax expense	$ 0.9	$ 29.3
Unrecognized tax benefits, exclusive of interest and penalties	6.7		$ 4.7
Unrecognized tax benefits from permanent tax adjustments that, if recognized, would affect the effective rate	4.0
Estimated unrecognized tax benefits resulting from possible resolution of reviews by domestic and international taxing authorities	3.4
Deferred tax asset valuation allowance	$ 46.2