Investment and Equity Securities - Amortized Cost and Fair Value of Available for Sale Securities Portfolio (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Due within twelve months, Amortized cost	$ 6,106
Due after one but within five years, Amortized Cost	17,917
Due after five but within ten years, Amortized Cost	95,052
Due after ten years, Amortized Cost	222,918
Available-for-sale Securities, Amortized Cost	341,993	$ 331,832
Due within twelve months, Estimated Fair Value	6,126
Due after one but within five years, Estimated Fair Value	17,463
Due after five but within ten years, Estimated Fair Value	89,310
Due after ten years, Estimated Fair Value	209,369
Available-for-sale Securities, Estimated Fair Value	$ 322,268	330,337
Due within twelve months, Book Yield	2.23%
Due after one but within five years, Book Yield	2.15%
Due after five but within ten years, Book Yield	1.19%
Due after ten years, Book Yield	1.52%
Total securities available for sale, Book Yield	1.47%
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Due after one but within five years, Amortized Cost	$ 4,791
Due after five but within ten years, Amortized Cost	26,619
Available-for-sale Securities, Amortized Cost	31,410	26,675
Due after one but within five years, Estimated Fair Value	4,686
Due after five but within ten years, Estimated Fair Value	24,703
Available-for-sale Securities, Estimated Fair Value	$ 29,389	26,381
Due after one but within five years, Book Yield	1.77%
Due after five but within ten years, Book Yield	1.24%
Total securities available for sale, Book Yield	1.32%
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Due within twelve months, Amortized cost	$ 4,001
Due after one but within five years, Amortized Cost	2,143
Due after five but within ten years, Amortized Cost	17,419
Due after ten years, Amortized Cost	18,727
Available-for-sale Securities, Amortized Cost	42,290	40,066
Due within twelve months, Estimated Fair Value	4,019
Due after one but within five years, Estimated Fair Value	2,050
Due after five but within ten years, Estimated Fair Value	16,980
Due after ten years, Estimated Fair Value	18,626
Available-for-sale Securities, Estimated Fair Value	$ 41,675	39,812
Due within twelve months, Book Yield	1.80%
Due after one but within five years, Book Yield	1.91%
Due after five but within ten years, Book Yield	0.80%
Due after ten years, Book Yield	1.09%
Total securities available for sale, Book Yield	1.08%
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Due after ten years, Amortized Cost	$ 42,161
Available-for-sale Securities, Amortized Cost	42,161	43,383
Due after ten years, Estimated Fair Value	42,261
Available-for-sale Securities, Estimated Fair Value	$ 42,261	44,198
Due after ten years, Book Yield	1.32%
Total securities available for sale, Book Yield	1.32%
Mortgage-backed Securities and CMO's [Member]
Schedule of Available-for-sale Securities [Line Items]
Due after one but within five years, Amortized Cost	$ 5,441
Due after five but within ten years, Amortized Cost	42,723
Due after ten years, Amortized Cost	76,585
Available-for-sale Securities, Amortized Cost	124,749	121,994
Due after one but within five years, Estimated Fair Value	5,391
Due after five but within ten years, Estimated Fair Value	39,741
Due after ten years, Estimated Fair Value	71,944
Available-for-sale Securities, Estimated Fair Value	$ 117,076	120,448
Due after one but within five years, Book Yield	3.46%
Due after five but within ten years, Book Yield	1.18%
Due after ten years, Book Yield	1.35%
Total securities available for sale, Book Yield	1.38%
State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Due within twelve months, Amortized cost	$ 105
Due after one but within five years, Amortized Cost	1,542
Due after five but within ten years, Amortized Cost	6,291
Due after ten years, Amortized Cost	85,445
Available-for-sale Securities, Amortized Cost	93,383	89,786
Due within twelve months, Estimated Fair Value	105
Due after one but within five years, Estimated Fair Value	1,528
Due after five but within ten years, Estimated Fair Value	5,903
Due after ten years, Estimated Fair Value	76,538
Available-for-sale Securities, Estimated Fair Value	$ 84,074	89,477
Due within twelve months, Book Yield	4.50%
Due after one but within five years, Book Yield	2.50%
Due after five but within ten years, Book Yield	1.96%
Due after ten years, Book Yield	1.86%
Total securities available for sale, Book Yield	1.88%
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Due within twelve months, Amortized cost	$ 2,000
Due after one but within five years, Amortized Cost	4,000
Due after five but within ten years, Amortized Cost	2,000
Available-for-sale Securities, Amortized Cost	8,000	9,928
Due within twelve months, Estimated Fair Value	2,002
Due after one but within five years, Estimated Fair Value	3,808
Due after five but within ten years, Estimated Fair Value	1,983
Available-for-sale Securities, Estimated Fair Value	$ 7,793	$ 10,021
Due within twelve months, Book Yield	2.98%
Due after one but within five years, Book Yield	0.83%
Due after five but within ten years, Book Yield	2.00%
Total securities available for sale, Book Yield	1.66%