Loans and Allowance for Credit Losses on Loans - Troubled Debt Restructurings by Class (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021 loan	Sep. 30, 2020 USD ($) loan	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($) loan
Troubled Debt Restructurings by Class
Number of loans modified as troubled debt restructurings during the period	0	7	1	10
Pre-modification Outstanding Recorded Investment		$ 510	$ 3	$ 520
Post-modification Outstanding Recorded Investment		$ 510	$ 3	$ 520
Commercial
Troubled Debt Restructurings by Class
Number of loans modified as troubled debt restructurings during the period		7	1	10
Pre-modification Outstanding Recorded Investment		$ 510	$ 3	$ 520
Post-modification Outstanding Recorded Investment		$ 510	$ 3	$ 520

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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Amount, after troubled debt restructuring, of modified financing receivable.

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Amount, before troubled debt restructuring, of financing receivable to be modified.

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