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Allowance for Credit Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2022 USD ($) loan | Dec. 31, 2021 USD ($) loan | Dec. 31, 2020 USD ($)
Financing Receivable, Past Due [Line Items] |  |  |
Total | $ 6,963,911 | $ 6,999,990 |
Non - performing | $ 52,524 | $ 66,291 | $ 146,774
Number of modified loans | loan | 3 | 8 |
Modified loans | $ 12,500 | $ 28,800 |
Current |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 6,905,239 | 6,927,943 |
Total Past Due Loans |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 58,672 | 72,047 |
30-59 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 4,281 | 3,085 |
60-89 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 751 | 2,671 |
Past Due 90+ Days Still Accruing |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | $ 1,116 | 0 |
Number of modified loans | loan | 5 |  |
Modified loans | $ 1,100 |  |
Commercial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 5,331,863 | 5,406,584 |
Commercial | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 2,705,799 | 2,690,528 |
Non - performing | 25,790 | 31,488 | 101,070
Commercial | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,458,506 | 1,513,523 |
Non - performing | 10,570 | 15,239 | 16,985
Commercial | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 383,237 | 424,755 |
Non - performing | 864 | 2,471 | 384
Commercial | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,141,236 | 1,135,693 |
Non - performing | 7,997 | 9,641 | 17,122
Commercial | Current | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 2,680,009 | 2,659,040 |
Commercial | Current | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,447,404 | 1,497,755 |
Commercial | Current | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 382,373 | 421,834 |
Commercial | Current | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,130,830 | 1,124,748 |
Commercial | Total Past Due Loans | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 25,790 | 31,488 |
Commercial | Total Past Due Loans | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 11,102 | 15,768 |
Commercial | Total Past Due Loans | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 864 | 2,921 |
Commercial | Total Past Due Loans | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 10,406 | 10,945 |
Commercial | 30-59 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | 30-59 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 3 | 529 |
Commercial | 30-59 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 450 |
Commercial | 30-59 Days Past Due | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,409 | 813 |
Commercial | 60-89 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | 60-89 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | 60-89 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | 60-89 Days Past Due | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 413 | 491 |
Commercial | Past Due 90+ Days Still Accruing | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | Past Due 90+ Days Still Accruing | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 529 | 0 |
Commercial | Past Due 90+ Days Still Accruing | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Commercial | Past Due 90+ Days Still Accruing | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 587 | 0 |
Consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,632,048 | 1,593,406 |
Consumer | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total |  | 357,900 |
Consumer | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,162,857 | 1,127,585 |
Non - performing | 7,178 | 7,294 | 11,117
Consumer | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 112,276 | 107,906 |
Non - performing | 125 | 158 | $ 96
Consumer | Current | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 1,152,858 | 1,117,074 |
Consumer | Current | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 111,765 | 107,492 |
Consumer | Total Past Due Loans | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 9,999 | 10,511 |
Consumer | Total Past Due Loans | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 511 | 414 |
Consumer | 30-59 Days Past Due | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 2,693 | 1,087 |
Consumer | 30-59 Days Past Due | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 176 | 206 |
Consumer | 60-89 Days Past Due | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 128 | 2,130 |
Consumer | 60-89 Days Past Due | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 210 | 50 |
Consumer | Past Due 90+ Days Still Accruing | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | 0 | 0 |
Consumer | Past Due 90+ Days Still Accruing | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total | $ 0 | $ 0 |

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