Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Allowances	$ 9,325	$ 9,654
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	26,493,335	26,308,668
Treasury stock, shares	3,979,735	3,803,043