Loans and Allowance for Credit Losses - Allowance for credit losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Loans and Allowance for Credit Losses
Balance at beginning of period	$ 63,480	$ 60,754	$ 67,338
Provision (credit) charged to expense	2,250	3,000	(6,700)
Losses charged off	(2,822)	(2,169)	(2,621)
Recoveries	1,762	1,895	2,737
Balance at end of period	64,670	63,480	60,754
Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			55,743
CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			11,595
Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	12,816	9,629	8,690
Provision (credit) charged to expense	(5,329)	3,187	939
Balance at end of period	7,487	12,816	9,629
Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			8,690
One- To Four-Family Residential and Construction
Loans and Allowance for Credit Losses
Balance at beginning of period	11,171	9,364	9,069
Provision (credit) charged to expense	(1,390)	1,652
Losses charged off	(31)	(40)	(190)
Recoveries	70	195	485
Balance at end of period	9,820	11,171	9,364
One- To Four-Family Residential and Construction | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			4,536
One- To Four-Family Residential and Construction | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			4,533
One- To Four-Family Residential and Construction | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	736	687	917
Provision (credit) charged to expense	(30)	49	(230)
Balance at end of period	706	736	687
One- To Four-Family Residential and Construction | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			917
Other Residential
Loans and Allowance for Credit Losses
Balance at beginning of period	12,110	10,502	15,207
Provision (credit) charged to expense	1,260	1,498	(4,797)
Recoveries		110	92
Balance at end of period	13,370	12,110	10,502
Other Residential | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			9,375
Other Residential | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			5,832
Other Residential | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	8,624	5,703	5,227
Provision (credit) charged to expense	(4,618)	2,921	476
Balance at end of period	4,006	8,624	5,703
Other Residential | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			5,227
Commercial Real Estate
Loans and Allowance for Credit Losses
Balance at beginning of period	27,096	28,604	31,176
Provision (credit) charged to expense	930	(1,465)	(2,478)
Losses charged off		(44)	(142)
Recoveries	145	1	48
Balance at end of period	28,171	27,096	28,604
Commercial Real Estate | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			33,707
Commercial Real Estate | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			(2,531)
Commercial Real Estate | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	416	367	354
Provision (credit) charged to expense	203	49	13
Balance at end of period	619	416	367
Commercial Real Estate | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			354
Commercial Construction
Loans and Allowance for Credit Losses
Balance at beginning of period	2,865	2,797	2,356
Provision (credit) charged to expense	(27)	152	575
Losses charged off		(84)	(154)
Recoveries	6		20
Balance at end of period	2,844	2,865	2,797
Commercial Construction | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			3,521
Commercial Construction | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			(1,165)
Commercial Construction | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	802	908	910
Provision (credit) charged to expense	(61)	(106)	(2)
Balance at end of period	741	802	908
Commercial Construction | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			910
Commercial Business
Loans and Allowance for Credit Losses
Balance at beginning of period	5,822	4,142	3,889
Provision (credit) charged to expense	1,909	1,491
Losses charged off	(1,037)	(51)	(81)
Recoveries	241	240	334
Balance at end of period	6,935	5,822	4,142
Commercial Business | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			2,390
Commercial Business | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			1,499
Commercial Business | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	1,734	1,582	935
Provision (credit) charged to expense	(775)	152	647
Balance at end of period	959	1,734	1,582
Commercial Business | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			935
Consumer
Loans and Allowance for Credit Losses
Balance at beginning of period	4,416	5,345	5,641
Provision (credit) charged to expense	(432)	(328)
Losses charged off	(1,754)	(1,950)	(2,054)
Recoveries	1,300	1,349	1,758
Balance at end of period	3,530	4,416	5,345
Consumer | Adjustment
Loans and Allowance for Credit Losses
Balance at beginning of period			2,214
Consumer | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			3,427
Consumer | Allowance for unfunded commitment
Loans and Allowance for Credit Losses
Balance at beginning of period	504	382	347
Provision (credit) charged to expense	(48)	122	35
Balance at end of period	$ 456	$ 504	382
Consumer | Allowance for unfunded commitment | CECL adoption
Loans and Allowance for Credit Losses
Balance at beginning of period			$ 347