Investment and Equity Securities - Gross Unrealized Losses and Fair Value of Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Fair Value	$ 84,655	$ 29,296
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Unrealized Losses	1,276	188
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Fair Value	4,078
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Unrealized Losses	63
Available-for-sale Securities, Gross unrealized losses, Fair Value	88,733	29,296
Available-for-sale Securities, Gross unrealized losses, Unrealized Losses	1,339	188
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Fair Value	24,012	5,061
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Unrealized Losses	455	26
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Fair Value	2,633
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Unrealized Losses	32
Available-for-sale Securities, Gross unrealized losses, Fair Value	26,645	5,061
Available-for-sale Securities, Gross unrealized losses, Unrealized Losses	487	26
GSE - Mortgage-backed Securities and CMO's [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Fair Value	18,829	10,263
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Unrealized Losses	174	68
Available-for-sale Securities, Gross unrealized losses, Fair Value	18,829	10,263
Available-for-sale Securities, Gross unrealized losses, Unrealized Losses	174	68
State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Fair Value	41,814	11,286
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Unrealized Losses	647	91
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Fair Value	1,445
Available-for-sale Securities, Gross unrealized losses, Twelve Months or More, Unrealized Losses	31
Available-for-sale Securities, Gross unrealized losses, Fair Value	43,259	11,286
Available-for-sale Securities, Gross unrealized losses, Unrealized Losses	$ 678	91
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Fair Value		2,686
Available-for-sale Securities, Gross unrealized losses, Less than Twelve Months, Unrealized Losses		3
Available-for-sale Securities, Gross unrealized losses, Fair Value		2,686
Available-for-sale Securities, Gross unrealized losses, Unrealized Losses		$ 3

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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-Name Accounting Standards Codification
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