Retirement Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Percentage of non-discretionary regular matching contribution of company	100.00%
Percentage of eligible compensation of deferral contribution, minimum	1.00%
Percentage of eligible compensation	80.00%
Percentage of eligible compensation of deferral contribution, maximum	6.00%
Matching contribution expense for defined contribution plan	$ 647	$ 694