Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Total
Beginning Balance at Dec. 31, 2016	$ 31	$ 63,103	$ 402,714	$ (57,982)		$ 113,267
Foreign currency translation adjustment, net of tax				40,096		15,899
Transfer from other comprehensive income into earnings				17		5
Net derivative instrument gain (loss), net of tax				37		17	$ 17
Net income			41,594			13,659	55,253
Dividends			(22,460)			(6,039)
Shares issued upon exercise of stock options		1,963
Purchase of subsidiary shares from noncontrolling interests
Stock-based compensation		938	722			531
End Balance at Dec. 31, 2017	31	66,004	422,570	(17,832)	$ (37,475)	137,339	570,637
Foreign currency translation adjustment, net of tax				(15,917)		(6,638)
Transfer from other comprehensive income into earnings				(37)
Net derivative instrument gain (loss), net of tax				136		39	39
Net income			53,793			15,922	69,715
Dividends			(28,356)			(8,706)
Shares issued upon exercise of stock options		3,406
Purchase of subsidiary shares from noncontrolling interests		(572)				(236)
Stock-based compensation		1,132	724			419
End Balance at Dec. 31, 2018	$ 31	69,970	448,731	(33,650)	(37,475)	138,139	585,746
Foreign currency translation adjustment, net of tax				(6,119)		(2,593)
Transfer from other comprehensive income into earnings				(136)
Net derivative instrument gain (loss), net of tax				52		(30)	(30)
Net income			60,249			15,821	76,070
Dividends			(36,349)			(9,654)
Shares issued upon exercise of stock options		4,458
Purchase of subsidiary shares from noncontrolling interests		(5,167)				(920)
Stock-based compensation		1,403	2,006			231
End Balance at Dec. 31, 2019		$ 70,664	$ 474,637	$ (39,853)	$ (37,475)	$ 140,994	$ 608,998