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, 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
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
Dividends common stock	(18,756)	0	0	(18,756)	0	0
Acqusition of noncontrolling interest	(31,787)	0	(21,151)	0	0	(10,636)
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
Net income	59,811	0	0	59,473	0	338
Amounts reported in other comprehensive income (loss)	(15,705)	0	0	0	(15,615)	(90)
Dividends common stock	(19,530)	0	0	(19,530)	0	0
Distributions to noncontrolling affiliate shareholders	(877)	0	0	0	0	(877)
Shares issued upon exercise of stock options and other	(423)	9	(432)	0	0	0
Shares issued for employee stock purchase plan	505	3	502	0	0	0
Equity based compensation plans	3,724	18	3,706	0	0	0
Balance at at Dec. 31, 2018	$ 436,369	$ 13,338	$ 97,304	$ 405,125	$ (80,715)	$ 1,317