CONSOLIDATED STATEMENTS OF Financial Position (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 28, 2014
Trade accounts receivable, allowances	$ 2,019	$ 1,968	$ 1,806
Treasury stock, shares	80,000	78,000	78,000
Common Stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944	$ 0.6944
Common stock, shares authorized	120,000,000	120,000,000	120,000,000
Common stock, shares issued	38,029,000	37,285,000	37,777,000
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944	$ 0.6944
Common stock, shares authorized	40,000,000	40,000,000	40,000,000
Common stock, shares issued	23,564,000	22,887,000	22,910,000