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Loans and Allowance for Credit Losses - Troubled Debt Restructuring Modifications (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 USD ($) contract | Dec. 31, 2019 USD ($) contract | Dec. 31, 2018 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |
Number of Contracts Modified | contract | 5 |  |
Pre-Modification Amortized Cost | $ 2,203 |  |
Post-Modification Amortized Cost | 2,195 |  |
Post-Modification Amortized Cost at Period End | $ 2,121 |  |
Commercial | Commercial and industrial |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |
Number of Contracts Modified | contract | 1 | 1 | 2
Pre-Modification Amortized Cost | $ 170 | $ 298 | $ 254
Post-Modification Amortized Cost | 162 | 298 | 245
Post-Modification Amortized Cost at Period End | $ 96 | $ 150 | $ 172
Commercial real estate | Commercial real estate, investor-owned |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |
Number of Contracts Modified | contract | 1 |  |
Pre-Modification Amortized Cost | $ 1,553 |  |
Post-Modification Amortized Cost | 1,553 |  |
Post-Modification Amortized Cost at Period End | $ 1,553 |  |
Residential loans | Home equity |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |
Number of Contracts Modified | contract | 1 |  |
Pre-Modification Amortized Cost | $ 276 |  |
Post-Modification Amortized Cost | 276 |  |
Post-Modification Amortized Cost at Period End | $ 271 |  |
Consumer loans | Installment and other consumer |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |
Number of Contracts Modified | contract | 2 |  |
Pre-Modification Amortized Cost | $ 204 |  |
Post-Modification Amortized Cost | 204 |  |
Post-Modification Amortized Cost at Period End | $ 201 |  |

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- Definition 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 + Details
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