v3.26.1
Loans - Loans HIP in past due status, non-performing status and accruing loans past-due 90 days or more by loan class (Parenthetical) (Detail) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Unearned Income $ 414,142 $ 421,624
Loans held-for-sale, at fair value 5,603 9,998
Loans held in portfolio 39,289,702 39,327,518
Non-accrual with no allowance 126,023 142,079
Federal Home Loan Bank    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Line Of Credit Facility Current Borrowing Capacity 4,200,000 4,000,000
FRB    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Line Of Credit Facility Current Borrowing Capacity 12,200,000 12,100,000
Current    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans held in portfolio 37,981,409 37,895,877
Reverse Mortgages | Current    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans held in portfolio 26,000 27,000
Residential mortgage loans insured    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Non-accrual with no allowance 43,000 47,000
Guarantees from FHA or VA    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Accruing loans past-due 90 days or more 196,000 197,000
Loans held in portfolio 3,300,000 3,200,000
Asset pledged as collateral    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans held in portfolio 22,900,000 22,700,000
Asset pledged as collateral | Federal Home Loan Bank    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans held in portfolio 7,400,000 7,500,000
Asset pledged as collateral | FRB    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Loans held in portfolio $ 15,500,000 $ 15,200,000