Stock-Based Compensation - Employee Stock Purchase Plan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under employee stock purchase plan (in shares)	90,681	118,548	90,681	118,548
Proceeds from issuance of shares under employee stock purchase plan			$ 960	$ 948
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock (as a percent)			85.00%
Proceeds from issuance of shares under employee stock purchase plan	$ 1,000		$ 1,000	$ 900