CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Stockholders' equity
Common stock, shares par value	$ 0.10	$ 0.10
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	3,420,000	3,420,000
Treasury stock, shares	1,592,000	1,594,000