Borrowings - Long-Term Debt (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Borrowings - Long-Term Debt [Line Items]
Long-Term Debt, Excluding Current Maturities	$ 112,814		$ 112,814		$ 112,740
Subordinated Debt	49,957		49,957		49,885
Interest Expense, Long-Term Debt	1,800	$ 1,200	5,000	$ 3,200
Capital Trust V Preferred Securites Due 2037 | Junior Subordinated Debt [Member]
Borrowings - Long-Term Debt [Line Items]
Long-Term Debt, Excluding Current Maturities	51,516		51,516		51,514
Central Bancorp Capital Trust I Securities Due in 2034 | Junior Subordinated Debt [Member]
Borrowings - Long-Term Debt [Line Items]
Long-Term Debt, Excluding Current Maturities	5,258		5,258		5,258
Central Bancorp Capital Trust II Securities Due in 2037 | Junior Subordinated Debt [Member]
Borrowings - Long-Term Debt [Line Items]
Long-Term Debt, Excluding Current Maturities	$ 6,083		$ 6,083		$ 6,083