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SEGMENT REPORTING AND REVENUE (Operating Segment Results) (Details) $ in Thousands | 3 Months Ended | 9 Months Ended | 21 Months Ended |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) segment | Apr. 01, 2025 USD ($) | Dec. 31, 2024 USD ($)
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Number of operating segments | segment |  |  |  |  | 2 |  |
Interest and dividend income | $ 503,437 | $ 324,528 | $ 1,319,645 | $ 908,330 |  |  |
Interest expense | 184,227 | 141,596 | 494,900 | 393,040 |  |  |
Net interest income | 319,210 | 182,932 | 824,745 | 515,290 |  |  |
Provision for credit losses | 16,233 | 2,603 | 139,578 | 32,592 |  |  |
Net interest income after provision for credit losses | 302,977 | 180,329 | 685,167 | 482,698 |  |  |
Noninterest income | 51,751 | 34,286 | 162,436 | 83,651 |  |  |
Noninterest expenses | 238,446 | 122,582 | 652,327 | 377,859 |  |  |
Income (loss) before income taxes | 116,282 | 92,033 | 195,276 | 188,490 |  |  |
LHFI, net of deferred fees and costs | 27,361,173 |  | 27,361,173 |  | $ 27,361,173 |  | $ 18,470,621
Goodwill | 1,726,386 |  | 1,726,386 |  | 1,726,386 |  | 1,214,053
Deposits | 30,665,324 |  | 30,665,324 |  | 30,665,324 |  | 20,397,619
American National |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | 288,842
Sandy Spring |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill | 512,333 |  | 512,333 |  | 512,333 | $ 512,333 |
Wholesale Banking | Sandy Spring |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill | 399,600 |  | 399,600 |  | 399,600 |  |
Consumer Banking | Sandy Spring |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill | 112,700 |  | 112,700 |  | 112,700 |  |
Operating segments | Wholesale Banking |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Interest and dividend income | 454,493 | 323,446 | 1,194,795 | 911,660 |  |  |
Interest expense | 293,637 | 222,349 | 776,220 | 634,741 |  |  |
Net interest income | 160,856 | 101,097 | 418,575 | 276,919 |  |  |
Provision for credit losses | 14,368 | 217 | 109,435 | 25,803 |  |  |
Net interest income after provision for credit losses | 146,488 | 100,880 | 309,140 | 251,116 |  |  |
Noninterest income | 29,000 | 10,773 | 64,450 | 29,913 |  |  |
Noninterest expenses | 92,982 | 50,521 | 232,787 | 142,926 |  |  |
Income (loss) before income taxes | 82,506 | 61,132 | 140,803 | 138,103 |  |  |
LHFI, net of deferred fees and costs | 22,852,155 |  | 22,852,155 |  | 22,852,155 |  | 15,514,640
Goodwill | 1,249,654 |  | 1,249,654 |  | 1,249,654 |  | 850,035
Deposits | 11,548,604 |  | 11,548,604 |  | 11,548,604 |  | 7,193,403
Operating segments | Wholesale Banking | Sandy Spring |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill | 399,600 |  | 399,600 |  | 399,600 |  |
Operating segments | Consumer Banking |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Interest and dividend income | 252,031 | 165,012 | 656,655 | 455,769 |  |  |
Interest expense | 137,295 | 85,900 | 353,285 | 231,411 |  |  |
Net interest income | 114,736 | 79,112 | 303,370 | 224,358 |  |  |
Provision for credit losses | 1,858 | 2,389 | 30,136 | 6,801 |  |  |
Net interest income after provision for credit losses | 112,878 | 76,723 | 273,234 | 217,557 |  |  |
Noninterest income | 19,945 | 15,721 | 54,240 | 43,589 |  |  |
Noninterest expenses | 108,850 | 64,694 | 274,932 | 185,672 |  |  |
Income (loss) before income taxes | 23,973 | 27,750 | 52,542 | 75,474 |  |  |
LHFI, net of deferred fees and costs | 5,257,652 |  | 5,257,652 |  | 5,257,652 |  | 3,085,207
Goodwill | 476,732 |  | 476,732 |  | 476,732 |  | 364,018
Deposits | 17,958,684 |  | 17,958,684 |  | 17,958,684 |  | 11,899,197
Operating segments | Consumer Banking | Sandy Spring |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Goodwill | 112,700 |  | 112,700 |  | 112,700 |  |
Corporate Other |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |
Interest and dividend income | (203,087) | (163,930) | (531,805) | (459,099) |  |  |
Interest expense | (246,705) | (166,653) | (634,605) | (473,112) |  |  |
Net interest income | 43,618 | 2,723 | 102,800 | 14,013 |  |  |
Provision for credit losses | 7 | (3) | 7 | (12) |  |  |
Net interest income after provision for credit losses | 43,611 | 2,726 | 102,793 | 14,025 |  |  |
Noninterest income | 2,806 | 7,792 | 43,746 | 10,149 |  |  |
Noninterest expenses | 36,614 | 7,367 | 144,608 | 49,261 |  |  |
Income (loss) before income taxes | 9,803 | $ 3,151 | 1,931 | $ (25,087) |  |  |
LHFI, net of deferred fees and costs | (748,634) |  | (748,634) |  | (748,634) |  | (129,226)
Goodwill | 0 |  | 0 |  | 0 |  | 0
Deposits | $ 1,158,036 |  | $ 1,158,036 |  | $ 1,158,036 |  | $ 1,305,019

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