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LOANS AND ALLOWANCE FOR LOAN AND LEASE LOSSES (Schedule for Allowance for Loan Loss Activity, by Portfolio Segment, Balances for Allowance for Credit Losses, and Loans Based on Impairment Methodology) (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Apr. 01, 2025 | Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Allowance for loan losses: |  |  |  |  |
Balance, beginning of period | $ 193,796 | $ 193,796 | $ 136,190 | $ 178,644 | $ 132,182
Loans charged off |  | (2,579) | (3,088) | (5,464) | (8,982)
Recoveries credited to allowance |  | 1,913 | 1,348 | 2,520 | 2,325
Provision charged to operations |  | 4,641 | 6,556 | 22,071 | 15,481
Balance, end of period |  | 315,574 | 158,131 | 315,574 | 158,131
American National |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  |  | (3,896) |  | (3,896)
Initial Provision - non-PCD loans |  |  | 13,229 |  | 13,229
Sandy Spring |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  | (28,265) |  | (28,265) |
Initial Provision - non-PCD loans |  | 89,538 |  | 89,538 |
Initial ACL recognized charge offs before acquisition |  | 34,500 |  |  |
Sandy Spring | PCD |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition | (28,265) |  |  |  |
Commercial Portfolio Segment [Member] |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Balance, beginning of period | 162,908 | 162,908 | 110,528 | 148,887 | 105,896
Loans charged off |  | (1,534) | (2,094) | (3,382) | (7,033)
Recoveries credited to allowance |  | 1,545 | 1,057 | 1,775 | 1,590
Provision charged to operations |  | 8,489 | 7,826 | 24,128 | 16,864
Balance, end of period |  | 257,403 | 131,139 | 257,403 | 131,139
Commercial Portfolio Segment [Member] | American National |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  |  | (2,609) |  | (2,609)
Initial Provision - non-PCD loans |  |  | 11,213 |  | 11,213
Commercial Portfolio Segment [Member] | Sandy Spring |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  | (21,255) |  | (21,255) |
Initial Provision - non-PCD loans |  | 64,740 |  | 64,740 |
Consumer Portfolio Segment [Member] |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Balance, beginning of period | $ 30,888 | 30,888 | 25,662 | 29,757 | 26,286
Loans charged off |  | (1,045) | (994) | (2,082) | (1,949)
Recoveries credited to allowance |  | 368 | 291 | 745 | 735
Provision charged to operations |  | (3,848) | (1,270) | (2,057) | (1,383)
Balance, end of period |  | 58,171 | 26,992 | 58,171 | 26,992
Consumer Portfolio Segment [Member] | American National |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  |  | (1,287) |  | (1,287)
Initial Provision - non-PCD loans |  |  | $ 2,016 |  | $ 2,016
Consumer Portfolio Segment [Member] | Sandy Spring |  |  |  |  |
Allowance for loan losses: |  |  |  |  |
Initial ACL at acquisition |  | (7,010) |  | (7,010) |
Initial Provision - non-PCD loans |  | $ 24,798 |  | $ 24,798 |

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