Consolidated Balance Sheets [Parenthetical] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts receivable (in dollars)	$ 555	$ 517
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	25,000,000	25,000,000
Common stock, shares outstanding (in shares)	12,500,006	12,449,253
Treasury stock (in shares)	619,667	619,667
Class B Convertible Common Stock
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	3,000,000	3,000,000
Common stock, shares outstanding (in shares)	1,022,887	1,025,158