CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Company Shares held by SERP [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2009	$ 4,510	$ 124,381	$ 4,551	$ (2,128)	$ 320,589	$ 357	$ 452,260
Balance (in shares) at Dec. 31, 2009	22,551,000
Net income					32,430	142	32,572
Other comprehensive income (loss)			3,495			100	3,595
Increase in ownership percentage of subsidiary						(1)	(1)
Stock-based compensation	1	2,394					2,395
Stock-based compensation (in shares)	6,000
Exercise of stock options, including tax benefit	18	1,992					2,010
Exercise of stock options, including tax benefit (in shares)	90,000
Purchase of Company stock held by SERP, net		64		(89)			(25)
Balance at Dec. 31, 2010	4,529	128,831	8,046	(2,217)	353,019	598	492,806
Balance (in shares) at Dec. 31, 2010	22,647,000
Net income					39,918	102	40,020
Other comprehensive income (loss)			(7,205)			(93)	(7,298)
Increase in ownership percentage of subsidiary						(1)	(1)
Stock-based compensation	1	2,799					2,800
Stock-based compensation (in shares)	5,000
Exercise of stock options, including tax benefit	12	1,110					1,122
Exercise of stock options, including tax benefit (in shares)	59,000
Purchase of Company stock held by SERP, net		4		(270)			(266)
Balance at Dec. 31, 2011	4,542	132,744	841	(2,487)	392,937	606	529,183
Balance (in shares) at Dec. 31, 2011	22,711,000						22,711,000
Dividends ($1.00 per share)		16			(22,806)		(22,790)
Net income					40,207	161	40,368
Other comprehensive income (loss)			(339)			15	(324)
Increase in ownership percentage of subsidiary						862	862
Stock-based compensation	1	1,284					1,285
Stock-based compensation (in shares)	6,000
Exercise of stock options, including tax benefit	17	604					621
Exercise of stock options, including tax benefit (in shares)	82,000
Withholding tax on vested RSU's		(834)					(834)
Purchase of Company stock held by SERP, net		(5)		(368)			(373)
Balance at Dec. 31, 2012	$ 4,560	$ 133,809	$ 502	$ (2,855)	$ 410,338	$ 1,644	$ 547,998
Balance (in shares) at Dec. 31, 2012	22,799,000						22,799,000