Consolidated Statements of Shareholders' 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]	Total
Balances at Dec. 31, 2015	$ 26	$ 4	$ 44,103	$ 65,313	$ (2,995)	$ (32,229)	$ 74,222
Purchase of shares of treasury stock						(601)	(601)
Issuance of common shares for the exercise of stock options			945				945
Issuance of restricted common shares, net of (forfeitures)
Non-cash stock compensation expense			1,929				1,929
Dividends declared				(14,324)			(14,324)
Acquisition of non-controlling interest			(252)				(252)
Other comprehensive income, foreign currency translation adjustment					369		369
Net income				20,518			20,518
Balances at Dec. 31, 2016	26	4	46,725	71,507	(2,626)	(32,830)	82,806
Purchase of shares of treasury stock						(4,123)	(4,123)
Issuance of common shares for the exercise of stock options			2,455				2,455
Issuance of restricted common shares, net of (forfeitures)
Non-cash stock compensation expense			1,845				1,845
Dividends declared				(16,876)			(16,876)
Other comprehensive income, foreign currency translation adjustment					991		991
Net income				22,943			22,943
Balances at Dec. 31, 2017	26	4	51,025	77,574	(1,635)	(36,953)	90,041
Purchase of shares of treasury stock						(7,950)	(7,950)
Issuance of common shares for the exercise of stock options			6,098				6,098
Issuance of restricted common shares, net of (forfeitures)
Non-cash stock compensation expense			1,514				1,514
Dividends declared				(29,751)			(29,751)
Other comprehensive income, foreign currency translation adjustment					(1,281)		(1,281)
Net income				30,047			30,047
Settlement of class B restricted common shares and stock options in connection with Recapitalization for cash of $3,271 and 90,369 class A common shares			(2,548)			(723)	(3,271)
Settlement of class B common shares in connection with Recapitalization (3,527,246 class B common shares exchanged for $69,099 cash and 3,527,246 class A common shares)	4		118,335			(187,438)	(69,099)
Retirement of class B common shares in connection with Recapitalization (retirement of 4,328,552 class B common shares)		(4)	(17,112)	(186,944)		204,060
Balances at Dec. 31, 2018	30		157,312	(106,339)	(2,916)	(29,004)	19,083
Cumulative effect adjustment for adoption of ASC 606, net of income tax				$ 2,735			$ 2,735