v3.25.2
Mortgage Loan Servicing, Origination, and Loans Held for Sale (Details) - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Mortgage Loan Servicing, Origination, and Loans Held for Sale          
Residential mortgages serviced for others $ 6,700,000,000   $ 6,700,000,000   $ 6,700,000,000
Contractually specified servicing fees earned 4,200,000 $ 4,300,000 8,500,000 $ 8,400,000  
Mortgage servicing rights 85,836,000   85,836,000   $ 89,795,000
Changes in the fair value of MSRs and its offsetting hedge.          
Increase/(decrease) in fair value of MSRs $ (1,689,000) $ 830,000 $ (4,770,000) $ 3,214,000  
Servicing Asset, Fair Value, Change in Fair Value, Valuation Input, Statement of Income or Comprehensive Income [Extensible Enumeration] Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax  
Decay of MSRs $ (2,284,000) $ (2,566,000) $ (3,312,000) $ (4,007,000)  
Gain (loss) related to derivatives 1,248,000 (1,424,000) 3,588,000 (4,004,000)  
Net effect on Consolidated Statements of Income $ (2,725,000) $ (3,160,000) $ (4,494,000) $ (4,797,000)  
Characteristics and sensitivity analysis of the MSR          
Composition of residential loans serviced for others 100.00%   100.00%   100.00%
Weighted average life (in years)     7 years 7 months 28 days   7 years 11 months 19 days
Constant Prepayment rate (CPR) (as a percent)     7.60%   7.00%
Estimated impact on fair value of a 10% increase, Constant Prepayment rate (CPR) $ (965,000)   $ (965,000)   $ (658,000)
Estimated impact on fair value of a 20% increase, Constant Prepayment rate (CPR) (1,900,000)   (1,900,000)   (1,298,000)
Estimated impact on fair value of a 10% decrease, Constant Prepayment rate (CPR) 1,005,000   1,005,000   666,000
Estimated impact on fair value of a 20% decrease, Constant Prepayment rate (CPR) 2,056,000   $ 2,056,000   $ 1,328,000
Weighted average discount rate (as a percent)     10.70%   10.90%
Estimated impact on fair value of a 10% increase, Weighted average discount rate (3,215,000)   $ (3,215,000)   $ (3,166,000)
Estimated impact on fair value of a 20% increase, Weighted average discount rate (6,362,000)   (6,362,000)   (6,339,000)
Estimated impact on fair value of a 10% decrease, Weighted average discount rate 3,167,000   3,167,000   3,022,000
Estimated impact on fair value of a 20% decrease, Weighted average discount rate 6,075,000   6,075,000   5,738,000
Effect on fair value due to change in interest rates:          
25 basis point increase 2,313,000   2,313,000   1,761,000
50 basis point increase 4,439,000   4,439,000   3,296,000
25 basis point decrease (2,389,000)   (2,389,000)   (1,952,000)
50 basis point decrease $ (4,803,000)   $ (4,803,000)   $ (4,052,000)
Fixed-rate mortgage loans          
Characteristics and sensitivity analysis of the MSR          
Composition of residential loans serviced for others 100.00%   100.00%   100.00%