v3.26.3
Derivative Financial Instruments Derivative Financial Instruments - Narrative (Details)
 9 Months Ended
Sep. 30, 2026
USD ($)
instrument
Dec. 31, 2025
USD ($)
instrument
Derivative [Line Items]    
Cash collateral pledged for derivatives $ 113,100,000 $ 29,500,000
CashCollateralPostedForDerivativesInLiabilityPosition 52,900,000 $ 7,600,000
Interest expense, long-term debt 870,000  
Derivative, amount of hedged item 373,900,000  
Fair value hedges, cumulative basis adjustments 23,200,000  
Senior Notes | 5.301% Senior Notes, Due February 2032    
Derivative [Line Items]    
Senior unsecured credit-linked notes $ 400,000,000.0  
Risk participation agreement - participant bank    
Derivative [Line Items]    
Instruments held | instrument 26 23
Non-hedging derivatives, notional amoount $ 520,000,000.0 $ 338,100,000
Maximum exposure $ 9,800,000 $ 510,000
Risk participation agreement - lead bank    
Derivative [Line Items]    
Instruments held | instrument 51 47
Non-hedging derivatives, notional amoount $ 636,100,000 $ 603,100,000
Interest rate contract    
Derivative [Line Items]    
Unrealized losses, net of tax to AOCI 49,700,000  
Amount reclassified from AOCI into interest income on loans 3,400,000  
Amount reclassified from AOCI as a decrease to interest income $ (24,700,000)  
Maximum period to hedge forecasted transactions 2 years  
Loans Receivable | Not Designated as Hedging Instrument    
Derivative [Line Items]    
Credit risk exposure, net of collateral pledged, relating to derivatives $ 14,500,000 $ 40,900,000