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	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned Income	$ 340,462	$ 295,156
Loans held-for-sale, at fair value	5,239	5,381
Notes Receivable Gross	34,029,313	32,077,769
Non-accrual with no allowance	144,321	177,104
Asset pledged as collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	13,700,000	7,400,000
Federal Home Loan Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line Of Credit Facility Current Borrowing Capacity	3,700,000	2,100,000
Federal Home Loan Bank | Asset pledged as collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	6,600,000	4,800,000
FRB Advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	7,100,000	2,600,000
Line Of Credit Facility Current Borrowing Capacity	4,600,000	1,400,000
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	32,821,825	30,783,152
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Receivable Gross	39,000	42,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	$ 115,000	$ 190,000