Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Minimum percentage of class A common stock declared dividend excess over class B dividend	10.00%
Options excluded from diluted earnings per share (in shares)	3,637,635
Class A Common Stock [Member]
Numerator:
Allocation of net income	$ 21,131	$ 43,609	$ 38,718
Denominator:
Weighted-average shares outstanding (in shares)	25,388,000	23,707,000	22,986,000
Basic earnings per share (in dollars per share)	$ 0.83	$ 1.84	$ 1.68
Numerator:
Allocation of net income	$ 21,131	$ 43,609	$ 38,718
Denominator:
Number of shares used in basic computation (in shares)	25,388,000	23,707,000	22,986,000
Weighted-average shares effect of dilutive securities
Director and employee stock options (in shares)	146,000	180,000	211,000
Number of shares used in diluted computation (in shares)	25,534,000	23,887,000	23,197,000
Diluted earnings per share (in dollars per share)	$ 0.83	$ 1.83	$ 1.67
Class B Common Stock [Member]
Numerator:
Allocation of net income	$ 4,123	$ 9,206	$ 8,434
Denominator:
Weighted-average shares outstanding (in shares)	5,577,000	5,577,000	5,577,000
Basic earnings per share (in dollars per share)	$ 0.74	$ 1.65	$ 1.51
Numerator:
Allocation of net income	$ 4,123	$ 9,206	$ 8,434
Denominator:
Number of shares used in basic computation (in shares)	5,577,000	5,577,000	5,577,000
Weighted-average shares effect of dilutive securities
Diluted earnings per share (in dollars per share)	$ 0.74	$ 1.65	$ 1.51