Investment and Equity Securities - Amortized Cost and Fair Value of Held to Maturity Securities Portfolio (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Held To Maturity Securities [Line Items]
Due within twelve months, Amortized Cost	$ 1,346
Due after one but within five years, Amortized Cost	1,048
Due after five but within ten years, Amortized Cost	15,000
Due after ten years, Amortized cost	13,328
Total Securities held for maturity, Amortized Cost	30,722
Due within twelve months, Estimated Fair Value	1,351
Due after one but within five years, Estimated Fair Value	1,051
Due after five but within ten years, Estimated Fair Value	14,539
Due after ten years, Estimated Fair Value	12,968
Total Securities held for maturity, Estimated Fair Value	$ 29,909	$ 32,045
Due within twelve months, Book Yield	2.08%
Due after one but within five years, Book Yield	2.34%
Due after five but within ten years, Book Yield	4.57%
Due after ten years, Book Yield	2.85%
Total Securities held for maturity, Book Yield	3.64%
U.S. Government Agencies [Member]
Schedule Of Held To Maturity Securities [Line Items]
Due after one but within five years, Amortized Cost	$ 152
Total Securities held for maturity, Amortized Cost	152
Due after one but within five years, Estimated Fair Value	149
Total Securities held for maturity, Estimated Fair Value	$ 149	176
Due after one but within five years, Book Yield	2.80%
Total Securities held for maturity, Book Yield	2.80%
State and Political Subdivisions [Member]
Schedule Of Held To Maturity Securities [Line Items]
Due within twelve months, Amortized Cost	$ 1,346
Due after one but within five years, Amortized Cost	896
Due after ten years, Amortized cost	13,328
Total Securities held for maturity, Amortized Cost	15,570
Due within twelve months, Estimated Fair Value	1,351
Due after one but within five years, Estimated Fair Value	902
Due after ten years, Estimated Fair Value	12,968
Total Securities held for maturity, Estimated Fair Value	$ 15,221	16,722
Due within twelve months, Book Yield	2.08%
Due after one but within five years, Book Yield	2.26%
Due after ten years, Book Yield	2.85%
Total Securities held for maturity, Book Yield	2.75%
Corporate Bonds [Member]
Schedule Of Held To Maturity Securities [Line Items]
Due after five but within ten years, Amortized Cost	$ 15,000
Total Securities held for maturity, Amortized Cost	15,000
Due after five but within ten years, Estimated Fair Value	14,539
Total Securities held for maturity, Estimated Fair Value	$ 14,539	$ 15,147
Due after five but within ten years, Book Yield	4.57%
Total Securities held for maturity, Book Yield	4.57%