Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Statement Of Financial Position [Abstract]
Allowance for loan losses	$ 10,510	$ 9,365
Preferred Stock, par value	$ 0.01	$ 0.01
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	18,133,095	18,133,095
Common stock, shares outstanding	11,732,222	11,596,263
Treasury stock, shares outstanding	6,400,873	6,536,832