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, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	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, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales	$ 191,600	$ 179,900	$ 193,500	$ 180,300	$ 189,600	$ 183,100	$ 198,000	$ 186,700	$ 194,300	$ 194,600	$ 191,900	$ 180,100	$ 745,345	$ 757,414	$ 760,941
Gross profit	72,900	68,600	75,300	74,800	72,400	68,000	77,400	72,800	79,000	79,700	78,500	68,300	291,635	290,554	305,396
Net income attributable to the Company	$ 8,000	$ 11,800	$ 11,200	$ 10,600	$ 8,700	$ 4,700	$ (7,400)	$ 11,500	$ 8,200	$ 9,500	$ (33,700)	$ 47,000	$ 41,569	$ 17,517	$ 30,977
Basic earnings per share	$ 0.26	$ 0.37	$ 0.35	$ 0.33	$ 0.27	$ 0.15	$ (0.23)	$ 0.36	$ 0.27	$ 0.30	$ (1.08)	$ 1.50	$ 1.31	$ 0.55	$ 0.99
Diluted earnings per share	$ 0.25	$ 0.37	$ 0.35	$ 0.33	$ 0.27	$ 0.15	$ (0.23)	$ 0.36	$ 0.26	$ 0.30	$ (1.08)	$ 1.49	$ 1.30	$ 0.55	$ 0.97	[1]
Cash dividends per share	$ 0.16	$ 0.16	$ 0.16	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.14	$ 0.14	$ 0.14	$ 0.14	$ 0.13
Maximum [Member]
Class A Common Stock prices:	$ 38.15	$ 38.53	$ 38.01	$ 37.59	$ 37.25	$ 36.53	$ 33.90	$ 29.87	$ 22.68	$ 22.78	$ 24.70	$ 25.90
Minimum [Member]
Class A Common Stock prices:	$ 32.46	$ 34.04	$ 33.67	$ 32.85	$ 33.81	$ 32.27	$ 27.48	$ 23.21	$ 20.11	$ 17.66	$ 17.15	$ 22.35

[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.