Short-Term Borrowed Funds - Summary of Short-Term Borrowed Funds (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Short Term Debt [Line Items]
Short-term borrowed funds	$ 1,379,000	$ 1,044,000
Short-term borrowed funds, weighted average rates at year end	4.56%	3.43%
Short-term borrowed funds, average balance during year	$ 1,077,000	$ 1,110,000
Short-term borrowed funds, weighted average rate during year	0.96%	0.92%
Federal Funds Purchased [Member]
Short Term Debt [Line Items]
Short-term borrowed funds, average balance during year	$ 4,000	$ 2,000
Short-term borrowed funds, weighted average rate during year	5.90%	3.16%
Master Notes and Other Short Term Borrowings [Member]
Short Term Debt [Line Items]
Short-term borrowed funds	$ 1,379,000	$ 1,044,000
Short-term borrowed funds, weighted average rates at year end	4.56%	3.43%
Short-term borrowed funds, average balance during year	$ 1,073,000	$ 1,108,000
Short-term borrowed funds, weighted average rate during year	0.94%	0.91%
Shortterm Debt Maximum Monthend Outstanding Amount	$ 2,094,000	$ 1,344,000