Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Common Class A [Member]	Common Class B [Member]	Total
Balances at Dec. 31, 2013	$ 25	$ 4	$ 42,192	$ 58,042	$ 302	$ (28,810)			$ 71,755
Purchase of treasury stock						(1,248)			(1,248)
Issuance of shares for the exercise of stock options			1,308						1,308
Tax benefit from the exercise of options and restricted stock			622						622
Issuance of restricted common shares, net of forfeitures	0	0							0
Non-cash stock compensation expense			742						742
Dividends declared				(2,512)					(2,512)
Other comprehensive income (loss), foreign currency translation adjustment					(1,075)				(1,075)
Net income				18,156			$ 9,062	$ 9,094	18,156
Balances at Dec. 31, 2014	25	4	44,864	73,686	(773)	(30,058)			87,748
Purchase of treasury stock						(2,171)			(2,171)
Issuance of shares for the exercise of stock options			406						406
Tax benefit from the exercise of options and restricted stock			240						240
Issuance of restricted common shares, net of forfeitures	1		(1)						0
Non-cash stock compensation expense			1,383						1,383
Dividends declared				(25,983)					(25,983)
Other comprehensive income (loss), foreign currency translation adjustment					(2,222)				(2,222)
Net income				17,610			8,759	8,851	17,610
Balances at Dec. 31, 2015	26	4	44,103	65,313	(2,995)	(32,229)			74,222
Acquisition of non-controlling interest			(2,789)						(2,789)
Purchase of treasury stock						(601)			(601)
Issuance of shares for the exercise of stock options			945						945
Issuance of restricted common shares, net of forfeitures	0	0							0
Non-cash stock compensation expense			1,929						1,929
Dividends declared				(14,324)					(14,324)
Other comprehensive income (loss), foreign currency translation adjustment					369				369
Net income				20,518			$ 10,178	$ 10,341	20,518
Balances at Dec. 31, 2016	$ 26	$ 4	46,725	$ 71,507	$ (2,626)	$ (32,830)			82,806
Acquisition of non-controlling interest			$ (252)						$ (252)