Quarterly Financial Data (Schedule of Quarterly Data) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011
Net sales	$ 189,600	$ 183,100	$ 198,000	$ 186,700	$ 194,300	$ 194,600	$ 191,900	$ 180,100	$ 197,400	$ 200,300	$ 189,700	$ 200,000	$ 757,414	$ 760,941		$ 787,287
Gross profit	72,400	68,000	77,400	72,800	79,000	79,700	78,500	68,300	77,000	78,100	73,900	85,200	290,554	305,396		314,166
Net income	$ 8,700	$ 4,700	$ (7,400)	$ 11,500	$ 8,200	$ 9,500	$ (33,700)	$ 47,000	$ (7,200)	$ 16,700	$ 8,800	$ 16,700	$ 17,517	$ 30,977		$ 34,938
Basic earnings per share	$ 0.27	$ 0.15	$ (0.23)	$ 0.36	$ 0.27	$ 0.30	$ (1.08)	$ 1.50	$ (0.23)	$ 0.53	$ 0.28	$ 0.54	$ 0.55	$ 0.99		$ 1.12
Diluted earnings per share	$ 0.27	$ 0.15	$ (0.23)	$ 0.36	$ 0.26	$ 0.30	$ (1.08)	$ 1.49	$ (0.23)	$ 0.53	$ 0.28	$ 0.53	$ 0.55	$ 0.97	[1]	$ 1.11
Cash dividends per share	$ 0.15	$ 0.15	$ 0.15	$ 0.14	$ 0.14	$ 0.14	$ 0.14	$ 0.13	$ 0.13	$ 0.13	$ 0.13	$ 0.12
Maximum [Member]
Class A Common Stock prices:	$ 37.25	$ 36.53	$ 33.90	$ 29.87	$ 22.68	$ 22.78	$ 24.70	$ 25.90	$ 25.70	$ 27.68	$ 27.90	$ 25.09
Minimum [Member]
Class A Common Stock prices:	$ 33.81	$ 32.27	$ 27.48	$ 23.21	$ 20.11	$ 17.66	$ 17.15	$ 22.35	$ 17.24	$ 17.82	$ 23.54	$ 21.84

[1] Due to a loss from continuing operations in 2012, the calculation of diluted income per share cannot be calculated by dividing net income by the diluted shares in the table above. See Statement of Income.