CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Company Shares Held by SERP [Member]	Retained Earnings [Member]	Non-Controlling Interest [Member]	Total
Balance at Dec. 31, 2012	$ 4,560	$ 133,809	$ 502	$ (2,855)	$ 409,874	$ 1,644	$ 547,534
Balance (in shares) at Dec. 31, 2012	22,799
Net income					39,042	172	39,214
Quarterly dividends		6			(6,862)		(6,856)
Other comprehensive loss			(5,396)			236	(5,160)
Change in ownership percentage of subsidiary						(802)	(802)
Capital contributed by minority shareholder						2,385	2,385
Stock-based compensation	$ 1	1,460					1,461
Stock-based compensation (in shares)	6
Exercise of stock options and RSU vesting, including tax benefit	$ 11	93					104
Exercise of stock options and RSU vesting, including tax benefit (in shares)	54
Withholding tax on vested RSUs		(782)					(782)
Sale of Company stock held by SERP, net		144		69			213
Balance at Dec. 31, 2013	$ 4,572	134,730	(4,894)	(2,786)	442,054	3,635	577,311
Balance (in shares) at Dec. 31, 2013	22,859
Net income					34,458	(252)	34,206
Quarterly dividends		8			(9,175)		(9,167)
Other comprehensive loss			(8,021)			565	(7,456)
Change in ownership percentage of subsidiary						(1,345)	(1,345)
Capital contributed by minority shareholder						1,583	1,583
Stock-based compensation	$ 1	1,199					1,200
Stock-based compensation (in shares)	5
Exercise of stock options and RSU vesting, including tax benefit	$ 13	855					868
Exercise of stock options and RSU vesting, including tax benefit (in shares)	66
Withholding tax on vested RSUs		(953)					(953)
Sale of Company stock held by SERP, net		48		(143)			(95)
Balance at Dec. 31, 2014	$ 4,586	135,887	(12,915)	(2,929)	467,337	4,186	$ 596,152
Balance (in shares) at Dec. 31, 2014	22,930						22,930
Net income					32,797	(831)	$ 31,966
Quarterly dividends		8			(9,201)		(9,193)
Other comprehensive loss			(10,649)			(772)	(11,421)
Change in ownership percentage of subsidiary						(663)	(663)
Stock-based compensation	$ 1	1,249					1,250
Stock-based compensation (in shares)	4
Exercise of stock options and RSU vesting, including tax benefit	$ 11	406					417
Exercise of stock options and RSU vesting, including tax benefit (in shares)	54
Withholding tax on vested RSUs		(600)					(600)
Sale of Company stock held by SERP, net		933		1,151			2,084
Other						(134)	(134)
Balance at Dec. 31, 2015	$ 4,598	$ 137,883	$ (23,564)	$ (1,778)	$ 490,933	$ 1,786	$ 609,858
Balance (in shares) at Dec. 31, 2015	22,988						22,988