Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Held-to-maturity securities, at amortized cost ,fair value	$ 1,671	$ 1,722
Loans receivable, allowance for loan losses	$ 15,875	$ 14,870
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares, issued	18,463,028	18,463,028
Common stock, shares, outstanding	17,327,942	17,125,969
Treasury stock,repurchased	1,135,086	1,337,059
Unearned compensation, ESOP shares	506,625	530,751