v3.25.1
Transfers of financial assets and servicing assets - Initial fair value of assets obtained as proceeds from residential mortgage loans securitized (Details) - USD ($)
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized $ 1,761,000 $ 2,250,000
Level 1    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Level 2    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 1,718,000 2,205,000
Level 3    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 43,000 45,000
Trading account debt securities    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 1,718,000 2,205,000
Trading account debt securities | Level 1    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Trading account debt securities | Level 2    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 1,718,000 2,205,000
Trading account debt securities | Level 3    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Trading account debt securities | GNMA    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 1,100,000
Trading account debt securities | GNMA | Level 1    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized   0
Trading account debt securities | GNMA | Level 2    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized   1,100,000
Trading account debt securities | GNMA | Level 3    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized   0
Trading account debt securities | FNMA    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 1,718,000 1,105,000
Trading account debt securities | FNMA | Level 1    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Trading account debt securities | FNMA | Level 2    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 1,718,000 1,105,000
Trading account debt securities | FNMA | Level 3    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Mortgage Servicing Rights    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 43,000 45,000
Mortgage Servicing Rights | Level 1    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Mortgage Servicing Rights | Level 2    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized 0 0
Mortgage Servicing Rights | Level 3    
Assets    
Initial fair value of the assets obtained as proceeds from residential mortgage loans securitized $ 43,000 $ 45,000