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Description of Business and Summary of Significant Accounting Policies - Schedule of Portfolio Segments Weighted Average Life, and Measures the Allowance for Credit Losses (Detail) - ASC 326 [Member] | 12 Months Ended
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Dec. 31, 2020
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 9 years
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 6 years
Real Estate [Member] | Construction and Development Less than 60 Months [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 3 years
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 1 year
Real Estate [Member] | Residential Real Estate First Lien [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 13 years
Real Estate [Member] | Residential Real Estate All Other [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 6 years
Real Estate [Member] | Farmland [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 12 years
Commercial and Agricultural Non-Real Estate [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 3 years
Consumer Non-real Estate [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 4 years
Oil and Gas [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 1 year
Other Loans [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 8 years
Pegasus Bank [Member] |
Financing Receivable Allowance For Credit Losses [Line Items] |
Loan Segment, Life (in years) | 4 years

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