Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Common Stock [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, 2017	$ 26	$ 4		$ 51,025	$ 77,574	$ (1,635)	$ (36,953)			$ 90,041
Purchase of shares							(1,272)			(1,272)
Issuance of common shares for the exercise of stock options				737						737
Issuance of restricted common shares, net of (forfeitures)
Non-cash stock compensation expense				454						454
Dividends declared					(4,223)					(4,223)
Other comprehensive income, foreign currency translation adjustment						(414)				(414)
Net income					7,306			$ 3,630	$ 3,676	7,306
Cumulative effect adjustment for adoption of ASC 606, net of income tax at Dec. 31, 2017					2,735					2,735
Balances at Mar. 31, 2018	$ 26	$ 4		52,216	83,392	(2,049)	(38,225)			95,364
Balances at Dec. 31, 2018			$ 30	157,312	(106,339)	(2,916)	(29,004)			19,083
Purchase of shares							(1,116)			(1,116)
Issuance of common shares for the exercise of stock options				633						633
Issuance of restricted common shares, net of (forfeitures)
Non-cash stock compensation expense				302						302
Dividends declared					(4,724)					(4,724)
Other comprehensive income, foreign currency translation adjustment						365				365
Net income					8,196					8,196
Balances at Mar. 31, 2019			$ 30	$ 158,247	$ (102,867)	$ (2,551)	$ (30,120)			$ 22,739