Debt - Additional Information (Short Term Debt) (Detail) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Securities sold under agreements to repurchase	$ 24,800,000	$ 28,800,000
Securities Sold under Agreements to Repurchase
Short-term Debt [Line Items]
Debt, weighted average interest rate	2.67%	1.48%
Securities Sold under Agreements to Repurchase | Mortgage Backed Securities, Other
Short-term Debt [Line Items]
Securities sold under agreements to repurchase	$ 21,200,000
Securities Sold under Agreements to Repurchase | Collateralized mortgage obligations, residential
Short-term Debt [Line Items]
Securities sold under agreements to repurchase	14,700,000
Federal Home Loan Bank of New York
Short-term Debt [Line Items]
Overnight borrowings	600,000,000
Line of Credit
Short-term Debt [Line Items]
Overnight federal funds borrowed	$ 89,400,000	$ 0
Debt, weighted average interest rate	6.14%
Overnight federal funds lines available for borrow	$ 250,000,000
Line of Credit | Federal Home Loan Bank of New York
Short-term Debt [Line Items]
Overnight borrowings		$ 700,000,000
Debt instrument, interest rate	5.61%	4.61%
Federal Reserve Bank of New York | Line of Credit
Short-term Debt [Line Items]
Borrowings with the Federal Reserve Bank	$ 0	$ 0