Commitments and Contingencies - Summary of Contract Amounts of Credit-related Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	$ 110,820	$ 87,337
Credit Enhancement Under FHLB of Chicago Mortgage Partnership Finance Program [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	1,099	1,095
Commitments to Sell Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	3,194	635
Overdraft Protection Program Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	3,734	3,758
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	150	150
Fixed Rate [Member] | Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	10,027	1,136
Fixed Rate [Member] | Credit Enhancement Under FHLB of Chicago Mortgage Partnership Finance Program [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	1,099	1,095
Fixed Rate [Member] | Commitments to Sell Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	3,194	635
Fixed Rate [Member] | Overdraft Protection Program Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	3,734	3,758
Variable Rate [Member] | Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	100,793	86,201
Variable Rate [Member] | Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fixed Rate	$ 150	$ 150