amortized cost, fair value and tax equivalent yield of securities, by maturity (Details) $ in Thousands	3 Months Ended
Mar. 31, 2021 USD ($)
U S Government Agency Notes 1 [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 4,497
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 4,512
Receivable with Imputed Interest, Effective Yield (Interest Rate)	2.32%
U S Government Agency Notes 2 [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 2,995
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 2,964
Receivable with Imputed Interest, Effective Yield (Interest Rate)	1.35%
U S Government Agency Notes Total [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 7,492
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 7,476
Receivable with Imputed Interest, Effective Yield (Interest Rate)	1.93%
U S States And Political Subdivisions 2 [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 3,038
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 3,188
Receivable with Imputed Interest, Effective Yield (Interest Rate)	2.71%
U S States And Political Subdivisions 3 [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 24,462
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 25,531
Receivable with Imputed Interest, Effective Yield (Interest Rate)	2.94%
U S States And Political Subdivisions Total [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 27,500
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 28,719
Receivable with Imputed Interest, Effective Yield (Interest Rate)	2.92%
US Government Agencies Debt Securities [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 81,628
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 82,237
Receivable with Imputed Interest, Effective Yield (Interest Rate)	1.94%
Corporate Debt Securities [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 8,750
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 8,911
Receivable with Imputed Interest, Effective Yield (Interest Rate)	5.22%
Available-for-sale Securities [Member]
Open Option Contracts Written [Line Items]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost	$ 125,370
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value	$ 127,343
Receivable with Imputed Interest, Effective Yield (Interest Rate)	2.39%

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date.

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