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Allowance for Credit Losses - Narrative (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Reserve for unfunded credits | $ 13,746,000 | $ 5,981,000
Allowance for credit loss, completion of revision, period from forecast start date | 5 years |
Adjustment of allowance for credit loss related to merger | $ 24,800,000 |
General allowance for loan and lease losses | 173,400,000 | 107,500,000
Increase (decrease) in general portion of the allowance for loan and lease losses | 65,900,000 |
Increase (decrease) in allowance for credit loss | 80,000,000.0 |
Specific allowance for loan and lease losses | 79,400,000 | 17,500,000
Specific allowance for loan and lease losses period increase (decrease) | 61,900,000 |
Total Loans and Leases | 18,029,552,000 | 9,779,288,000
Interest income on nonaccrual loans | 0 | 0
Holdco Merger |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Specific allowance for loan and lease losses period increase (decrease) | 44,800,000 |
Legacy Berkshire Portfolio |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Adjustment of allowance for credit loss related to merger | 5,600,000 |
Definite Loss |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Total Loans and Leases |  | 0
Commercial Real Estate Loans | Holdco Merger |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Specific allowance for loan and lease losses period increase (decrease) | 26,400,000 |
C&I Loans | Holdco Merger |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Specific allowance for loan and lease losses period increase (decrease) | 18,200,000 |
Consumer Loans | Holdco Merger |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Specific allowance for loan and lease losses period increase (decrease) | 200,000 |
Commercial Loan |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Total Loans and Leases | 2,784,152,000 | 1,211,714,000
Equipment financing |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Total Loans and Leases | 1,163,211,000 | 1,294,950,000
Total |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Total Loans and Leases | 14,100,820,000 | $ 8,287,145,000
Total | Definite Loss |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Total Loans and Leases | $ 0 |
Minimum |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Allowance for credit loss, start of revision, period from forecast start date | 2 years |
Maximum |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |
Allowance for credit loss, start of revision, period from forecast start date | 3 years |

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