Loans and Allowance for Credit Losses - Troubled debt restructurings (TDRs) (Details) $ in Thousands	Mar. 31, 2022 USD ($) contract	Dec. 31, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	50	64
Financing Receivable, Troubled Debt Restructuring | $	$ 3,730	$ 3,851
Construction and land development
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	1	1
Financing Receivable, Troubled Debt Restructuring | $	$ 12	$ 15
One- to four-family residential construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	18	22
Financing Receivable, Troubled Debt Restructuring | $	$ 1,609	$ 1,638
Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	2	2
Financing Receivable, Troubled Debt Restructuring | $	$ 1,774	$ 1,811
Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	29	39
Financing Receivable, Troubled Debt Restructuring | $	$ 335	$ 387
Accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	24	38
Financing Receivable, Troubled Debt Restructuring | $	$ 898	$ 1,002
Accruing | Construction and land development
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	1	1
Financing Receivable, Troubled Debt Restructuring | $	$ 12	$ 15
Accruing | One- to four-family residential construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	7	10
Financing Receivable, Troubled Debt Restructuring | $	$ 616	$ 579
Accruing | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract		1
Financing Receivable, Troubled Debt Restructuring | $		$ 85
Accruing | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	16	26
Financing Receivable, Troubled Debt Restructuring | $	$ 270	$ 323
Non-accruing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	26	26
Financing Receivable, Troubled Debt Restructuring | $	$ 2,832	$ 2,849
Non-accruing | One- to four-family residential construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	11	12
Financing Receivable, Troubled Debt Restructuring | $	$ 993	$ 1,059
Non-accruing | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	2	1
Financing Receivable, Troubled Debt Restructuring | $	$ 1,774	$ 1,726
Non-accruing | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Number of Contracts | contract	13	13
Financing Receivable, Troubled Debt Restructuring | $	$ 65	$ 64