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, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned Income	$ 367,423	$ 355,908
Loans held-for-sale, at fair value	5,352	4,301
Notes Receivable Gross	35,118,738	35,064,971
Non-accrual with no allowance	143,027	125,958
Federal Home Loan Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line Of Credit Facility Current Borrowing Capacity	3,800,000	3,500,000
FRB Advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line Of Credit Facility Current Borrowing Capacity	4,600,000	4,400,000
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	33,846,890	33,716,900
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	37,000	38,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	93,000	106,000
Asset pledged as collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	14,000,000	14,200,000
Asset pledged as collateral | Federal Home Loan Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	7,000,000	7,000,000
Asset pledged as collateral | FRB Advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	$ 7,000,000	$ 7,200,000