Borrowings - Additional Information (Detail) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Securities sold under agreements to repurchase	$ 25,700,000	$ 28,800,000
Advances from the FHLB	25,000,000	25,000,000
Securities Sold under Agreements to Repurchase
Debt Instrument [Line Items]
Pledged assets separately reported, mortgage-related securities available-for-sale or held-for-investment	22,300,000
Collateralized mortgage obligations, residential | Securities Sold under Agreements to Repurchase
Debt Instrument [Line Items]
Pledged assets separately reported, mortgage-related securities available-for-sale or held-for-investment	15,200,000
Line of Credit
Debt Instrument [Line Items]
Federal funds available for borrowing	250,000,000
Overnight federal funds borrowed	0	0
Line of Credit | Federal Reserve Bank of New York
Debt Instrument [Line Items]
Federal reserve bank, advances, amount of advances by branch	0	0
Federal Home Loan Bank of New York | Line of Credit
Debt Instrument [Line Items]
Overnight borrowings	$ 913,000,000	$ 700,000,000
Collateralized FHLB Advances | Weighted Average
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, branch of FHLB Bank, interest rate		0.77%