Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Taxes
Interest expense	$ 204	$ 0	$ 39
Unrecognized tax benefits	2,055	0	0	$ 1,087
Accrued interest	204
Unrecognized tax benefits if recognized would impact the reported effective tax rate	711
State and Local Jurisdiction
Income Taxes
Decrease in income tax expense due to state tax flow through of accelerated depreciation	$ 1,344	$ 1,539	$ 1,976