Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]
Beginning balance at Sep. 30, 2018	$ 70,980	$ 16,783	$ 54,197
Beginning balance, Shares at Sep. 30, 2018		7,897,145
Net income	3,067		3,067
Dividends declared	(871)		(871)
Employee and director restricted stock vested, Shares		21,563
Repurchase of vested employee restricted stock for tax withholding	(36)	$ (31)	(5)
Repurchase of vested employee restricted stock for tax withholding, Shares		(2,685)
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	4	$ 4
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		296
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	13	$ 13
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		1,207
Stock-based compensation	568	$ 568
Ending balance at Dec. 31, 2018	73,725	$ 17,337	56,388
Ending balance, shares at Dec. 31, 2018		7,917,526
Beginning balance at Sep. 30, 2018	70,980	$ 16,783	54,197
Beginning balance, Shares at Sep. 30, 2018		7,897,145
Net income	5,967
Ending balance at Mar. 31, 2019	76,317	$ 17,900	58,417
Ending balance, shares at Mar. 31, 2019		7,919,394
Beginning balance at Dec. 31, 2018	73,725	$ 17,337	56,388
Beginning balance, Shares at Dec. 31, 2018		7,917,526
Net income	2,900		2,900
Dividends declared	(871)		(871)
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	6	$ 6
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		534
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	14	$ 14
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		1,334
Stock-based compensation	557	$ 557
Employee restricted stock forfeiture	(14)	(14)
Ending balance at Mar. 31, 2019	76,317	$ 17,900	58,417
Ending balance, shares at Mar. 31, 2019		7,919,394
Beginning balance at Sep. 30, 2019	75,528	$ 17,673	57,855
Beginning balance, Shares at Sep. 30, 2019		7,527,040
Net income	2,628		2,628
Dividends declared	(1,032)		(1,032)
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	20	$ 20
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		1,702
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	18	$ 18
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		1,596
Stock-based compensation	447	$ 447
Shares repurchased pursuant to stock buyback program	(685)	$ (128)	(557)
Shares repurchased pursuant to stock buyback program, Shares		(64,787)
Ending balance at Dec. 31, 2019	76,924	$ 18,030	58,894
Ending balance, shares at Dec. 31, 2019		7,465,551
Beginning balance at Sep. 30, 2019	75,528	$ 17,673	57,855
Beginning balance, Shares at Sep. 30, 2019		7,527,040
Net income	4,598
Ending balance at Mar. 31, 2020	76,320	$ 18,089	58,231
Ending balance, shares at Mar. 31, 2020		7,261,323
Beginning balance at Dec. 31, 2019	76,924	$ 18,030	58,894
Beginning balance, Shares at Dec. 31, 2019		7,465,551
Net income	1,970		1,970
Dividends declared	(1,011)		(1,011)
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	0	$ 0
Shares issued for auto-investments pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		46
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan	18	$ 18
Shares issued for dividend reinvestment pursuant to the 2018 Dividend Reinvestment and Stock Purchase Plan, Shares		1,835
Stock-based compensation	447	$ 447
Shares repurchased pursuant to stock buyback program	(2,028)	$ (406)	(1,622)
Shares repurchased pursuant to stock buyback program, Shares		(206,109)
Ending balance at Mar. 31, 2020	$ 76,320	$ 18,089	$ 58,231
Ending balance, shares at Mar. 31, 2020		7,261,323