CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands	Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive loss [Member]	Treasury stock [Member]	Noncontrolling interest [Member]	Total
Balance, beginning at Dec. 31, 2015	$ 31	$ 62,030	$ 388,434	$ (48,091)	$ (36,817)	$ 110,800
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued upon exercise of stock options		402
Sale of subsidiary shares to noncontrolling interest		(35)				463
Net income			13,165			4,012	$ 17,177
Dividends			(9,315)			(4,863)
Share based compensation		421
Foreign currency translation adjustment, net of tax				5,670		2,443	8,113
Balance, ending at Jun. 30, 2016	31	62,818	392,284	(42,421)	(36,817)	112,855	488,750
Balance, beginning at Dec. 31, 2016	31	63,103	402,714	(57,982)	(37,475)	113,267	483,658
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued upon exercise of stock options		625
Net income			20,117			7,261	27,378
Dividends			(10,598)			(5,947)
Share based compensation		468	347			254
Foreign currency translation adjustment, net of tax				24,106		9,466	33,572
Transfer from other comprehensive income into earnings				17		5
Net derivative instrument gain, net of tax				453		168
Balance, ending at Jun. 30, 2017	$ 31	$ 64,196	$ 412,580	$ (33,406)	$ (37,475)	$ 124,474	$ 530,400