Fair Value Of Financial Instruments (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	$ 682,984	$ 734,318
State And Municipals [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	308,857	327,171
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	682,984	734,318
Fair Value, Measurements, Recurring [Member] | Premises and Facilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	3,800
Fair Value, Measurements, Recurring [Member] | State And Municipals [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	308,857	327,171
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	1,002	970
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | State And Municipals [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-Sale Securities, Fair value	$ 1,002	$ 970
Number of non-rated bond anticipation notes | item	7
Maturity period	1 year