CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Trade accounts receivable, allowances	$ 1,949	$ 1,820
Treasury stock, shares	90,000	88,000
Common Stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944
Common stock, shares authorized	120,000	120,000
Common stock, shares issued	38,836	38,544
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944
Common stock, shares authorized	40,000	40,000
Common stock, shares issued	26,287	25,584