Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total		Stock Options	Number of Shares	Number of Shares Stock Options	Unearned Shares Issued to ESOP	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at beginning of period (in shares) at Sep. 30, 2017				7,361,077
Balance at beginning of period at Sep. 30, 2017	$ 111,000			$ 13,286		$ (397)	$ 98,235	$ (124)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,614						3,614
Other comprehensive income (loss)	$ (12)							(12)
Exercise of stock options (in shares)	6,250			6,250
Exercise of stock options	$ 61			$ 61
Common stock dividends ($0.11 and $0.23 per share, respectively)	(810)						(810)
Earned ESOP shares, net of income taxes	215			$ 149		66
Stock option compensation expense			$ 44		$ 44
Balance at end of period (in shares) at Dec. 31, 2017				7,367,327
Balance at end of period at Dec. 31, 2017	114,112			$ 13,540		(331)	101,039	(136)	[1]
Balance at beginning of period (in shares) at Sep. 30, 2018				7,401,177
Balance at beginning of period at Sep. 30, 2018	124,657	[2]		$ 14,394		(133)	110,525	(129)	[1]
Balance at beginning of period (in shares) at Sep. 30, 2018				7,401,177
Balance at beginning of period at Sep. 30, 2018	124,657	[2]		$ 14,394		(133)	110,525	(129)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,615						5,615
Other comprehensive income (loss)	$ (79)							(79)
Exercise of stock options (in shares)	7,400			7,400
Exercise of stock options	$ 71			$ 71
Common stock dividends ($0.11 and $0.23 per share, respectively)	(1,911)						(1,911)
Earned ESOP shares, net of income taxes	$ 232			$ 166		66
Stock option compensation expense			$ 53		$ 53
Common stock issued for business combination (in shares)	904,826
Common stock issued for business combination	$ 28,267
Balance at end of period (in shares) at Dec. 31, 2018				8,313,403
Balance at end of period at Dec. 31, 2018	156,905			$ 42,951		$ (67)	114,166	(145)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2016-01 | Accounting Standards Update 2016-01	$ 0						$ (63)	$ 63

[1] All amounts are net of income taxes.

[2] Derived from audited consolidated financial statements.