Income Taxes - NOL and Capital Loss Carryforwards (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Income tax
Estimated effective income tax rate (as a percent)	39.00%	12.00%	12.00%
Net operating and capital loss carryforwards	$ 51.4
Tax credit carryforwards	28.0
Income tax benefit for discrete items	$ 4.2	$ 1.3
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, 2035