CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 29, 2012	Dec. 31, 2011	Oct. 01, 2011
Trade accounts receivable, allowances	$ 3,501	$ 1,731	$ 2,621
Treasury stock, shares	73	71	71
Common stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944	$ 0.6944
Common stock, shares authorized	120,000	120,000	120,000
Common stock, shares issued	36,998	36,479	36,807
Class B common stock
Common stock, par value (in dollars per share)	$ 0.6944	$ 0.6944	$ 0.6944
Common stock, shares authorized	40,000	40,000	40,000
Common stock, shares issued	21,629	21,025	21,032