Quarterly report [Sections 13 or 15(d)]

GOODWILL AND INTANGIBLE ASSETS (Narrative) (Details)

v3.25.1
GOODWILL AND INTANGIBLE ASSETS (Narrative) (Details)
 3 Months Ended 6 Months Ended
Mar. 31, 2025
USD ($)
segment
Mar. 31, 2024
USD ($)
Dec. 31, 2024
USD ($)
Apr. 01, 2024
USD ($)
Finite-Lived Intangible Assets [Line Items]        
Number of operating segments | segment 2      
Goodwill $ 1,214,053,000   $ 1,214,053,000  
Intangible Assets 79,165,000   84,563,000  
Impairment of goodwill or intangible assets 0      
Intangible assets, amortization expense $ 5,398,000 $ 1,895,000    
Core Deposits [Member] | Minimum [Member]        
Finite-Lived Intangible Assets [Line Items]        
Intangible assets, amortization period (years) 4 years      
Core Deposits [Member] | Maximum [Member]        
Finite-Lived Intangible Assets [Line Items]        
Intangible assets, amortization period (years) 10 years      
Other Intangible Assets [Member] | Minimum [Member]        
Finite-Lived Intangible Assets [Line Items]        
Intangible assets, amortization period (years) 4 years      
Other Intangible Assets [Member] | Maximum [Member]        
Finite-Lived Intangible Assets [Line Items]        
Intangible assets, amortization period (years) 10 years      
American National        
Finite-Lived Intangible Assets [Line Items]        
Goodwill $ 288,800,000     $ 288,842,000
Increase in goodwill     $ 6,500,000  
American National | Wholesale Banking        
Finite-Lived Intangible Assets [Line Items]        
Goodwill       210,800,000
American National | Consumer Banking        
Finite-Lived Intangible Assets [Line Items]        
Goodwill       $ 78,000,000