Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
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	18,463,028	18,463,028
Unearned compensation, ESOP shares	639,312	675,501