Net Income Per Share Of Common Stock	12 Months Ended
	Dec. 31, 2020
Net Income Per Share Of Common Stock [Abstract]
Net Income Per Share Of Common Stock	11. NET INCOME PER SHARE OF COMMON STOCK The computation of net income per share of common stock is based on the average number of common shares outstanding during each year, adjusted in all periods presented for the declaration of a 5% stock dividend declared in 2019, and a 10% stock dividend declared in 2018. The average number of shares used in computing net income per share of common stock at December 31, 2020, 2019, and 2018 was 22,642,057 shares, 22,555,240 shares, and 22,507,701 shares, respectively.