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Allowance for Credit Losses - Schedule of Activity in the Allowance for Credit Losses by Loan Portfolio (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | $ 387,380 | $ 312,109 | $ 357,448 | $ 299,653 | $ 299,653
Other adjustments | (60) | (105) | (15) | (139) |
Charge-offs | (10,477) | (7,524) | (36,344) | (24,565) |
Recoveries | 2,359 | 4,355 | 5,731 | 9,368 |
Provision for credit losses | 19,948 | 6,193 | 71,589 | 30,711 |
Allowance for credit losses at period end | 399,150 | 315,028 | 399,150 | 315,028 | $ 357,448
Individually measured | 15,302 | 10,043 | 15,302 | 10,043 |
Collectively measured | 383,848 | 304,985 | 383,848 | 304,985 |
Loans at period end, individually evaluated for impairment | 77,937 | 105,365 | 77,937 | 105,365 |
Loans at period end, collectively evaluated for impairment | 41,196,917 | 37,905,355 | 41,196,917 | 37,905,355 |
Loans held-for-investment | 171,178 | 156,893 | 171,178 | 156,893 |
Accounting Standards Update 2016-13 |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Cumulative effect adjustment from the adoption of ASU 2016-13, net of tax |  |  |  |  | Accounting Standards Update 2016-13
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | 741 |  |
Allowance for credit losses at period end |  |  |  |  | $ 741
Commercial |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 143,142 | 142,919 | 142,769 | 119,307 | 119,307
Other adjustments | 0 | 0 | 0 | 0 |
Charge-offs | (2,427) | (780) | (10,599) | (11,122) |
Recoveries | 1,162 | 2,523 | 2,059 | 4,057 |
Provision for credit losses | 9,611 | (9,346) | 17,148 | 23,074 |
Allowance for credit losses at period end | 151,488 | 135,316 | 151,488 | 135,316 | 142,769
Individually measured | 9,773 | 8,866 | 9,773 | 8,866 |
Collectively measured | 141,715 | 126,450 | 141,715 | 126,450 |
Loans at period end, individually evaluated for impairment | 43,569 | 46,547 | 43,569 | 46,547 |
Loans at period end, collectively evaluated for impairment | 12,681,904 | 12,212,703 | 12,681,904 | 12,212,703 |
Loans held-for-investment | 0 | 0 | 0 | 0 |
Commercial | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | 111 |  |
Allowance for credit losses at period end |  |  |  |  | 111
Commercial Real Estate |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 215,696 | 143,732 | 184,352 | 144,583 | 144,583
Other adjustments | 0 | 0 | 0 | 0 |
Charge-offs | (1,713) | (24) | (9,842) | (841) |
Recoveries | 243 | 55 | 368 | 640 |
Provision for credit losses | 1,492 | 6,955 | 39,484 | 6,336 |
Allowance for credit losses at period end | 215,718 | 150,718 | 215,718 | 150,718 | 184,352
Individually measured | 5,408 | 378 | 5,408 | 378 |
Collectively measured | 210,310 | 150,340 | 210,310 | 150,340 |
Loans at period end, individually evaluated for impairment | 17,043 | 27,882 | 17,043 | 27,882 |
Loans at period end, collectively evaluated for impairment | 10,929,137 | 9,550,302 | 10,929,137 | 9,550,302 |
Loans held-for-investment | 0 | 0 | 0 | 0 |
Commercial Real Estate | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | 1,356 |  |
Allowance for credit losses at period end |  |  |  |  | 1,356
Home Equity |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 6,967 | 6,990 | 7,573 | 10,699 | 10,699
Other adjustments | 0 | 0 | 0 | 0 |
Charge-offs | (227) | (43) | (227) | (432) |
Recoveries | 33 | 38 | 105 | 254 |
Provision for credit losses | 307 | 70 | (338) | (3,466) |
Allowance for credit losses at period end | 7,080 | 7,055 | 7,080 | 7,055 | 7,573
Individually measured | 0 | 71 | 0 | 71 |
Collectively measured | 7,080 | 6,984 | 7,080 | 6,984 |
Loans at period end, individually evaluated for impairment | 1,363 | 11,421 | 1,363 | 11,421 |
Loans at period end, collectively evaluated for impairment | 341,895 | 317,401 | 341,895 | 317,401 |
Loans held-for-investment | 0 | 0 | 0 | 0 |
Home Equity | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | (33) |  |
Allowance for credit losses at period end |  |  |  |  | (33)
Residential real estate |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 12,252 | 10,479 | 11,585 | 8,782 | 8,782
Other adjustments | 0 | 0 | 0 | 0 |
Charge-offs | (78) | (5) | (78) | (471) |
Recoveries | 1 | 60 | 11 | 71 |
Provision for credit losses | 484 | 489 | 1,833 | 2,641 |
Allowance for credit losses at period end | 12,659 | 11,023 | 12,659 | 11,023 | 11,585
Individually measured | 109 | 727 | 109 | 727 |
Collectively measured | 12,550 | 10,296 | 12,550 | 10,296 |
Loans at period end, individually evaluated for impairment | 15,946 | 19,440 | 15,946 | 19,440 |
Loans at period end, collectively evaluated for impairment | 2,520,479 | 2,059,126 | 2,520,479 | 2,059,126 |
Loans held-for-investment | 171,178 | 156,893 | 171,178 | 156,893 |
Residential real estate | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | (692) |  |
Allowance for credit losses at period end |  |  |  |  | (692)
Premium Finance Receivables |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 9,046 | 7,502 | 10,671 | 15,859 | 15,859
Other adjustments | (60) | (105) | (15) | (139) |
Charge-offs | (5,848) | (6,037) | (15,151) | (10,618) |
Recoveries | 906 | 1,648 | 3,119 | 4,243 |
Provision for credit losses | 7,776 | 7,424 | 13,196 | 1,087 |
Allowance for credit losses at period end | 11,820 | 10,432 | 11,820 | 10,432 | 10,671
Individually measured | 0 | 0 | 0 | 0 |
Collectively measured | 11,820 | 10,432 | 11,820 | 10,432 |
Loans at period end, individually evaluated for impairment | 0 | 0 | 0 | 0 |
Loans at period end, collectively evaluated for impairment | 14,654,555 | 13,718,196 | 14,654,555 | 13,718,196 |
Loans held-for-investment | 0 | 0 | 0 | 0 |
Premium Finance Receivables | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | 0 |  |
Allowance for credit losses at period end |  |  |  |  | 0
Consumer and other |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period | 277 | 487 | 498 | 423 | 423
Other adjustments | 0 | 0 | 0 | 0 |
Charge-offs | (184) | (635) | (447) | (1,081) |
Recoveries | 14 | 31 | 69 | 103 |
Provision for credit losses | 278 | 601 | 266 | 1,039 |
Allowance for credit losses at period end | 385 | 484 | 385 | 484 | 498
Individually measured | 12 | 1 | 12 | 1 |
Collectively measured | 373 | 483 | 373 | 483 |
Loans at period end, individually evaluated for impairment | 16 | 75 | 16 | 75 |
Loans at period end, collectively evaluated for impairment | 68,947 | 47,627 | 68,947 | 47,627 |
Loans held-for-investment | $ 0 | $ 0 | 0 | $ 0 |
Consumer and other | Cumulative Effect, Period of Adoption, Adjustment |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Roll Forward] |  |  |  |  |
Allowance for credit losses at beginning of period |  |  | $ (1) |  |
Allowance for credit losses at period end |  |  |  |  | $ (1)

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