Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Balance at at Dec. 31, 2014	$ 365,135	$ 13,301	$ 99,056	$ 299,524	$ (54,406)	$ 7,660
Net income	52,706	0	0	51,180	0	1,526
Amounts reported in other comprehensive income (loss)	(19,547)	0	0	0	(18,910)	(637)
Repurchases of common stock	(7,276)	(87)	0	(7,189)	0	0
Dividends common stock	(16,775)	0	0	(16,775)	0	0
Acqusition of noncontrolling interest	0	0	0	0	0	0
Disposition of noncontrolling interest	(351)	0	0	0	0	(351)
Shares issued upon exercise of stock options and other	619	17	602	0	0	0
Shares issued for employee stock purchase plan	429	6	423	0	0	0
Equity based compensation plans	5,919	51	5,868	0	0	0
Excess tax benefit from stock option exercises	384	0	384	0	0	0
Balance at at Dec. 31, 2015	381,243	13,288	106,333	326,740	(73,316)	8,198
Net income	63,039	0	0	61,403	0	1,636
Amounts reported in other comprehensive income (loss)	(14,152)	0	0	0	(14,091)	(61)
Repurchases of common stock	(5,859)	(84)	0	(5,775)	0	0
Dividends common stock	(17,954)	0	0	(17,954)	0	0
Acquisition of noncontrolling interest	73	0	0	0	0	73
Disposition of noncontrolling interest	0	0	0	0	0	0
Shares issued upon exercise of stock options and other	(1,302)	11	(1,313)	0	0	0
Shares issued for employee stock purchase plan	491	6	485	0	0	0
Equity based compensation plans	6,349	57	6,292	0	0	0
Excess tax benefit from stock option exercises	678	0	678	0	0	0
Balance at at Dec. 31, 2016	412,606	13,278	112,475	364,414	(87,407)	9,846
Net income	22,300	0	0	20,278	0	2,022
Amounts reported in other comprehensive income (loss)	23,021	0	0	0	22,307	714
Repurchases of common stock	0	0	0	0	0	0
Dividends common stock	(18,756)	0	0	(18,756)	0	0
Acqusition of noncontrolling interest	(31,787)	0	(21,151)	0	0	(10,636)
Disposition of noncontrolling interest	0	0	0	0	0	0
Shares issued upon exercise of stock options and other	(2,451)	5	(2,456)	0	0	0
Shares issued for employee stock purchase plan	495	4	491	0	0	0
Equity based compensation plans	4,190	21	4,169	0	0	0
Excess tax benefit from stock option exercises	0	0	0	0	0	0
Balance at at Dec. 31, 2017	$ 409,618	$ 13,308	$ 93,528	$ 365,936	$ (65,100)	$ 1,946