Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts receivable, reserves	$ 1,134	$ 1,284
Preferred Stock, par (in dollars per share)	$ 1	$ 1
Preferred Stock, authorized	1,000,000	1,000,000
Preferred Stock, issued	0	0
Cost of Common Stock in treasury, shares	48,794	124,758
Common Stock [Member]
Common Stock, par (in dollars per share)	$ 1	$ 1
Common Stock, authorized	50,000,000	50,000,000
Common Stock, issued	24,339,666	23,264,259
Class B Common Stock [Member]
Common Stock, par (in dollars per share)	$ 1	$ 1
Common Stock, authorized	33,000,000	33,000,000
Common Stock, issued	7,130,125	7,925,254
Common Stock, outstanding	7,130,125	7,925,254