Loans - Narrative (Details)			12 Months Ended
	Dec. 31, 2023 USD ($) loan	Jan. 06, 2022 USD ($)	Dec. 31, 2023 USD ($) loan contract	Dec. 31, 2022 USD ($) contract loan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable on loans	$ 29,100,000		$ 29,100,000	$ 24,500,000
Net deferred loan fees	(1,800,000)		(1,800,000)	2,100,000
Overdraft balances included in home equity and consumer loans	619,000		619,000	1,300,000
Residential loans pledged for potential borrowings at the Federal Home Loan Bank of New York	4,580,000,000		4,580,000,000	2,890,000,000
Financing receivable, nonaccrual, in the process of foreclosure	621,000		621,000	898,000
PCD loans		$ 124,431,000
Financing receivable, excluding accrued interest, modified in period, amount			$ 0
Financing receivable, accrual, troubled debt restructuring				$ 2,600,000
Financing receivable, troubled debt restructuring, subsequent default, number of contracts | contract			0	0
Loans to related parties	69,100,000		$ 69,100,000	$ 67,500,000
Loans to related parties, additions			10,100,000
Repayment of loan from related parties			8,600,000
Loans held for sale	664,000		664,000	536,000
Residential real estate acquired through disclosure	0		0	0
Other repossessed assets owned	0		0	0
Writedown of other repossessed assets			$ 0	$ 0	$ 0
1st Constitution Bancorp
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCD loans	$ 69,500,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans still accruing | loan	0		0	0