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Loans and Allowance for Credit Losses - Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | $ 55,180 | $ 54,053 |
Unpaid Principal Balance | 64,720 | 65,331 |
Related Allowance | 395 | 4,906 |
Average Recorded Investment | 47,071 | 50,728 |
Interest Income Recognized | 898 | 639 |
Commercial Financial Agricultural And Other With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 3,720 | 2,025 |
Unpaid Principal Balance | 10,303 | 2,725 |
Average Recorded Investment | 9,240 | 6,371 |
Interest Income Recognized | 389 | 80 |
Commercial Financial Agricultural And Other With No Related Allowance [Member] | Time and demand loans |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 3,720 | 2,025 |
Unpaid Principal Balance | 10,303 | 2,725 |
Average Recorded Investment | 9,240 | 6,371 |
Interest Income Recognized | 389 | 80 |
Real Estate Construction With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 45 | 54 |
Unpaid Principal Balance | 53 | 53 |
Average Recorded Investment | 53 | 146 |
Interest Income Recognized | 0 | 14 |
Residential real estate with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 9,365 | 10,939 |
Unpaid Principal Balance | 11,294 | 13,258 |
Average Recorded Investment | 10,315 | 11,913 |
Interest Income Recognized | 375 | 335 |
Residential real estate with no related allowance recorded [Member] | Senior Lien |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 5,200 | 6,062 |
Unpaid Principal Balance | 6,337 | 7,575 |
Average Recorded Investment | 5,674 | 6,605 |
Interest Income Recognized | 279 | 241 |
Residential real estate with no related allowance recorded [Member] | Junior Lien |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 4,165 | 4,877 |
Unpaid Principal Balance | 4,957 | 5,683 |
Average Recorded Investment | 4,641 | 5,308 |
Interest Income Recognized | 96 | 94 |
Commercial Real Estate With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 40,591 | 20,650 |
Unpaid Principal Balance | 41,525 | 23,641 |
Average Recorded Investment | 26,235 | 22,287 |
Interest Income Recognized | 119 | 184 |
Commercial Real Estate With No Related Allowance [Member] | Multifamily |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 14,677 | 1 |
Unpaid Principal Balance | 14,677 | 82 |
Average Recorded Investment | 1,223 | 1 |
Interest Income Recognized | 0 | 0 |
Commercial Real Estate With No Related Allowance [Member] | Nonowner Occupied Commercial Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 24,581 | 16,786 |
Unpaid Principal Balance | 25,310 | 19,459 |
Average Recorded Investment | 22,668 | 18,536 |
Interest Income Recognized | 28 | 82 |
Commercial Real Estate With No Related Allowance [Member] | Owner Occupied Commercial Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 1,333 | 3,863 |
Unpaid Principal Balance | 1,538 | 4,100 |
Average Recorded Investment | 2,344 | 3,750 |
Interest Income Recognized | 91 | 102 |
Loans To Individuals With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 446 | 418 |
Unpaid Principal Balance | 485 | 447 |
Average Recorded Investment | 479 | 470 |
Interest Income Recognized | 15 | 13 |
Loans To Individuals With No Related Allowance [Member] | Automobiles |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 388 | 405 |
Unpaid Principal Balance | 422 | 430 |
Average Recorded Investment | 425 | 447 |
Interest Income Recognized | 15 | 13 |
Loans To Individuals With No Related Allowance [Member] | Other consumer loans |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 58 | 13 |
Unpaid Principal Balance | 63 | 17 |
Average Recorded Investment | 54 | 23 |
Interest Income Recognized | 0 | 0 |
Subtotal with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 54,167 | 34,086 |
Unpaid Principal Balance | 63,660 | 40,124 |
Average Recorded Investment | 46,322 | 41,187 |
Interest Income Recognized | 898 | 626 |
Commercial, financial, agricultural and other With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 327 | 4,210 |
Unpaid Principal Balance | 349 | 9,377 |
Related Allowance | 307 | 1,268 |
Average Recorded Investment | 84 | 1,544 |
Interest Income Recognized | 0 | 3 |
Commercial, financial, agricultural and other With an allowance recorded [Member] | Time and demand loans |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 327 | 4,210 |
Unpaid Principal Balance | 349 | 9,377 |
Related Allowance | 307 | 1,268 |
Average Recorded Investment | 84 | 1,544 |
Interest Income Recognized | 0 | 3 |
Real estate construction with an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Residential real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Residential real estate With an allowance recorded [Member] | Senior Lien |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Residential real estate With an allowance recorded [Member] | Junior Lien |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Commercial real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 686 | 15,757 |
Unpaid Principal Balance | 711 | 15,830 |
Related Allowance | 88 | 3,638 |
Average Recorded Investment | 665 | 7,997 |
Interest Income Recognized | 0 | 10 |
Commercial real estate With an allowance recorded [Member] | Multifamily |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 421 | 459 |
Unpaid Principal Balance | 446 | 470 |
Related Allowance | 88 | 116 |
Average Recorded Investment | 444 | 395 |
Interest Income Recognized | 0 | 0 |
Commercial real estate With an allowance recorded [Member] | Nonowner Occupied Commercial Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 15,060 |
Unpaid Principal Balance | 0 | 15,122 |
Related Allowance | 0 | 3,508 |
Average Recorded Investment | 0 | 7,363 |
Interest Income Recognized | 0 | 0 |
Commercial real estate With an allowance recorded [Member] | Owner Occupied Commercial Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 265 | 238 |
Unpaid Principal Balance | 265 | 238 |
Related Allowance | 0 | 14 |
Average Recorded Investment | 221 | 239 |
Interest Income Recognized | 0 | 10 |
Loans to individuals With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Loans to individuals With an allowance recorded [Member] | Automobiles |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Loans to individuals With an allowance recorded [Member] | Other consumer loans |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 0 | 0 |
Unpaid Principal Balance | 0 | 0 |
Related Allowance | 0 | 0 |
Average Recorded Investment | 0 | 0 |
Interest Income Recognized | 0 | 0 |
Subtotal With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Recorded Investment | 1,013 | 19,967 |
Unpaid Principal Balance | 1,060 | 25,207 |
Related Allowance | 395 | 4,906 |
Average Recorded Investment | 749 | 9,541 |
Interest Income Recognized | $ 0 | $ 13 |
Originated Loans [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | $ 27,154
Interest Income Recognized |  |  | 684
Originated Loans [Member] | Commercial Financial Agricultural And Other With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 2,411
Interest Income Recognized |  |  | 66
Originated Loans [Member] | Real Estate Construction With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Originated Loans [Member] | Residential real estate with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 10,819
Interest Income Recognized |  |  | 365
Originated Loans [Member] | Commercial Real Estate With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 7,455
Interest Income Recognized |  |  | 156
Originated Loans [Member] | Loans To Individuals With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 371
Interest Income Recognized |  |  | 17
Originated Loans [Member] | Subtotal with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 21,056
Interest Income Recognized |  |  | 604
Originated Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 4,110
Interest Income Recognized |  |  | 77
Originated Loans [Member] | Real estate construction with an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Originated Loans [Member] | Residential real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 241
Interest Income Recognized |  |  | 0
Originated Loans [Member] | Commercial real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 1,747
Interest Income Recognized |  |  | 3
Originated Loans [Member] | Loans to individuals With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Originated Loans [Member] | Subtotal With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 6,098
Interest Income Recognized |  |  | 80
Acquired Loans [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 5,225
Interest Income Recognized |  |  | 26
Acquired Loans [Member] | Commercial Financial Agricultural And Other With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 2,479
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Real Estate Construction With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Residential real estate with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 1,986
Interest Income Recognized |  |  | 8
Acquired Loans [Member] | Commercial Real Estate With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 747
Interest Income Recognized |  |  | 18
Acquired Loans [Member] | Loans To Individuals With No Related Allowance [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 13
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Subtotal with no related allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 5,225
Interest Income Recognized |  |  | 26
Acquired Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Real estate construction with an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Residential real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Commercial real estate With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Loans to individuals With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | 0
Acquired Loans [Member] | Subtotal With an allowance recorded [Member] |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Average Recorded Investment |  |  | 0
Interest Income Recognized |  |  | $ 0

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