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Investments - Investment Securities Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Held-to-Maturity, Gross Unrealized Losses, Total	$ 657	$ 5
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	67,825	4,648
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	657	5
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	67,825	4,648
Fair Value of Investments with Unrealized Losses, Less Than 12 months		4,648
Gross Unrealized Loss, Less Than 12 Months		5
Fair Value of Investments with Unrealized Losses, Total		4,648
Gross Unrealized Losses, Total		5
Corporate Bonds [Member]
Marketable Securities [Line Items]
Held-to-Maturity, Gross Unrealized Losses, Total	272	3
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	36,443	2,515
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	272	3
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	36,443	2,515
U.S. Agency-Based Mortgage-Backed Securities [Member]
Marketable Securities [Line Items]
Held-to-Maturity, Gross Unrealized Losses, Total	13	2
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	1,146	2,133
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	13	2
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	1,146	2,133
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months	23,465
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months	240
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total	23,465
Held-to-Maturity, Gross Unrealized Losses, Total	$ 240
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Marketable Securities [Line Items]
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Less Than 12 Months		6,771
Held-to-Maturity, Gross Unrealized Losses, Less Than 12 Months		132
Held-to-Maturity, Fair Value of Investments with Unrealized Losses, Total		6,771
Held-to-Maturity, Gross Unrealized Losses, Total		$ 132

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