Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Preferred Stock, par value per share	$ 5.00	$ 5.00
Preferred Stock, shares authorized	2,000,000	2,000,000
Preferred Stock, shares issued	0	0
Common Stock, shares outstanding	32,300,000	32,200,000	32,100,000
Treasury stock, shares	8,418,620	8,431,335
Common Class A [Member]
Common Stock, par value per share	$ 0.001	$ 0.001
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	37,450,329	37,395,753
Common Class B [Member]
Common Stock, par value per share	$ 0.001	$ 0.001
Common Stock, shares authorized	25,000,000	25,000,000
Common Stock, shares issued	3,233,998	3,233,998
Common Stock, shares outstanding	3,233,998	3,233,998