Income Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Anti-dilutive securities
Common stock, authorized shares	30,000,000
Common stock, shares outstanding	5,668,123
Income per share of common stock:
Net income for basic and diluted income per common share	$ 8,668	$ 7,031
Weighted-average shares for basic income per common share (in shares)	5,667,000	5,651,000
Effect of dilutive securities:
Employee and director stock options (in shares)	10,000	13,000
Adjusted weighted-average shares and assumed exercises for diluted income per common share (in shares)	5,677,000	5,664,000
Basic net income per common share (in dollars per share)	$ 1.53	$ 1.24
Diluted net income per common share (in dollars per share)	$ 1.53	$ 1.24
Options
Anti-dilutive securities
Anti-dilutive shares of common stock excluded from the calculation of dilutive securities	10,000	7,000