Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 121,315	$ 120,473
Accumulated depreciation	(87,756)	(79,318)
Property and equipment, net	33,559	41,155
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,811	1,811
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,256	10,157
Process Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	107,162	106,919
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,591	1,551
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 495	$ 35