Nature of Operations and Summary of Significant Accounting Policies - Basic and Diluted EPS (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2015
Earnings Per Share [Abstract]
Net income (loss)	$ 1,021,000	$ 2,588,000	$ 3,415,000	$ 1,394,000	$ 1,724,000	$ 2,114,000	$ 1,630,000	$ 1,575,000	$ 8,418,000		$ 7,043,000		$ (1,819,000)
Net Income Diluted									$ 8,418,000		$ 7,043,000		$ (1,819,000)
Weighted average common shares outstanding	14,414,000	14,400,000	14,390,000	14,380,000	14,368,000	14,333,000	14,320,000	14,307,000	14,396,000		14,334,000		14,283,000
Common Stock Equivalents									284,000		190,000		0
Diluted shares outstanding	14,700,000	14,699,000	14,597,000	14,589,000	14,616,000	14,550,000	14,489,000	14,425,000	14,680,000		14,524,000		14,283,000
Basic earnings per common share:
Basic earnings per share	$ 0.07	$ 0.18	$ 0.24	$ 0.10	$ 0.12	$ 0.15	$ 0.11	$ 0.11	$ 0.58	[1]	$ 0.49	[1]	$ (0.13)	[1]
Diluted earnings per common share:
Diluted earnings per share	$ 0.07	$ 0.18	$ 0.23	$ 0.10	$ 0.12	$ 0.15	$ 0.11	$ 0.11	$ 0.57	[1]	$ 0.48	[1]	$ (0.13)	[1]

[1] 2016 and 2015 adjusted for three-for-two stock split