Securities (Narrative) (Details)	Sep. 30, 2021 USD ($) investment	Dec. 31, 2020 USD ($) investment	Dec. 31, 2009 USD ($)
Debt Securities, Available-for-sale [Line Items]
Carrying value of securities pledged to secure repurchase agreements, public and trust deposits and other by law	$ 190,514,000	$ 237,506,000
Allowance for Credit Losses	0	0
Accrued interest receivable on available-for-sale debt securities	8,143,000	5,954,000
Original amount in non-controlling investment security in a single banking organization	353,000	$ 353,000	$ 1,350,000
Additional impairment on equity securities recognized through earnings	$ 0		$ 997,000
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Number of non-controlling investments in a single banking organization \| investment	1	1

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Carrying value of securities sold under agreements to repurchase and deposits received for securities loaned.

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Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security without readily determinable fair value.

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