Consolidated Balance Sheets Details (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Loans, allowance for loan losses	$ 7,470	$ 5,762
Accumulated depreciation	$ 23,774	$ 22,570
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, shares issued (in shares)	7,596,351	7,568,053
Common stock, shares outstanding (in shares)	6,176,556	6,157,692
Treasury stock, shares (in shares)	1,419,795	1,410,361