Consolidated Statements of Changes in Equity (Unaudited) - USD ($) $ in Thousands	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock	Noncontrolling interest	Total
Beginning Balance at Dec. 31, 2018	$ 31	$ 69,970	$ 448,731	$ (33,650)		$ 138,139
Foreign currency translation adjustment, net of tax				(2,229)		(765)
Transfer from other comprehensive income into earnings				(136)
Net derivative instrument loss, net of tax				244		39	$ 39
Net income			31,211			9,366	40,577
Dividends			(17,298)			(9,654)
Shares issued upon exercise of stock options		2,281
Share-based compensation (adjustment)		701	1,218			135
Purchase of subsidiary shares from noncontrolling interest		(4,610)				(1,477)
Transfer of subsidiary shares purchased
Ending Balance at Jun. 30, 2019	31	68,342	463,862	(35,771)	$ (37,475)	135,783	594,772
Beginning Balance at Dec. 31, 2019	31	70,664	474,637	(39,853)		140,994	608,998
Foreign currency translation adjustment, net of tax				(661)		(173)
Transfer from other comprehensive income into earnings				(52)
Net derivative instrument loss, net of tax						(19)	(19)
Net income			6,941			3,375	10,316
Dividends			(10,406)			(324)
Shares issued upon exercise of stock options	1	656
Share-based compensation (adjustment)		855	290			128
Purchase of subsidiary shares from noncontrolling interest
Transfer of subsidiary shares purchased		360				(139)
Ending Balance at Jun. 30, 2020	$ 32	$ 72,535	$ 471,462	$ (40,566)	$ (37,475)	$ 143,842	$ 609,830