Annual report [Section 13 and 15(d), not S-K Item 405]

GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill and Intangible Assets by Operating Segment) (Details)

v3.25.4
GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill and Intangible Assets by Operating Segment) (Details) - USD ($)
$ in Thousands
Dec. 31, 2025
Apr. 01, 2025
Dec. 31, 2024
Apr. 01, 2024
Finite-Lived Intangible Assets [Line Items]        
Goodwill $ 1,733,287   $ 1,214,053  
Intangible Assets 315,544   84,563  
American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 288,800   288,842 $ 288,842
Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 519,234 $ 519,234    
Wholesale Banking | American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 210,800      
Wholesale Banking | Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 404,900      
Consumer Banking | American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 78,000      
Consumer Banking | Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 114,300      
Operating segments | Wholesale Banking        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 1,254,979   850,035  
Intangible Assets 50,916   8,714  
Operating segments | Wholesale Banking | American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill     210,800  
Intangible Assets     8,400  
Operating segments | Wholesale Banking | Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 404,900      
Intangible Assets 46,300      
Operating segments | Consumer Banking        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 478,308   364,018  
Intangible Assets 621   778  
Operating segments | Consumer Banking | American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill     78,000  
Operating segments | Consumer Banking | Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 114,300      
Corporate Other        
Finite-Lived Intangible Assets [Line Items]        
Goodwill 0   0  
Intangible Assets 264,007   75,071  
Corporate Other | Sandy Spring        
Finite-Lived Intangible Assets [Line Items]        
Intangible Assets $ 244,400   $ 76,300