Loans Receivable and Allowance for Credit Losses - Impaired Loans by Class (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Impaired Financing Receivable 1 [Line Items]
Charge offs	$ 8	$ 15
Year 2023
Impaired Financing Receivable 1 [Line Items]
Charge offs	6		$ 15
Prior years
Impaired Financing Receivable 1 [Line Items]
Charge offs	2
One- to four-family residential
Impaired Financing Receivable 1 [Line Items]
Charge offs	2
One- to four-family residential | Prior years
Impaired Financing Receivable 1 [Line Items]
Charge offs	2
Loans on Deposit Accounts
Impaired Financing Receivable 1 [Line Items]
Charge offs	3
Loans on Deposit Accounts | Year 2023
Impaired Financing Receivable 1 [Line Items]
Charge offs	3		$ 15
Consumer and other
Impaired Financing Receivable 1 [Line Items]
Charge offs	3
Consumer and other | Year 2023
Impaired Financing Receivable 1 [Line Items]
Charge offs	$ 3