CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Class A [Member]	Class B [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Common Stock [Member] Class A [Member]	Common Stock [Member] Class B [Member]	Additional Paid-in Capital [Member]
Balance at Dec. 31, 2012	$ 215,362			$ 195,183	$ (1,427)	$ 217	$ 937	$ 20,452
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,576)			(2,576)
Issuance of restricted common stock	0						16	(16)
Forfeiture of restricted common stock	0						(2)	2
Repurchase/retirement of Class B common stock	(3,356)		$ (10,000)				(18)	(3,338)
Foreign currency translation adjustment	977				977
Unrealized holding gains on marketable securities arising during the year net of taxes	87				87
Reclassification adjustment for gain (loss) on sale of marketable securities included in net earnings, net of tax of $-, $- and ($37)	(61)				(61)
Increase (Reduction) in APIC pool associated with tax benefit (deficiencies) related to restricted stock awards	(65)							(65)
Stock-based compensation expense	1,879							1,879
Change in unfunded SERP liability, net of taxes	1,069				1,069
Net earnings	15,908	$ 2,868	13,040	15,908
Balance at Dec. 31, 2013	228,702			207,993	645	217	933	18,914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,665)			(2,665)
Issuance of restricted common stock	0						38	(38)
Forfeiture of restricted common stock	0						(2)	2
Foreign currency translation adjustment	(11,255)				(11,255)
Unrealized holding gains on marketable securities arising during the year net of taxes	147				147
Reclassification adjustment for gain (loss) on sale of marketable securities included in net earnings, net of tax of $-, $- and ($37)	0
Increase (Reduction) in APIC pool associated with tax benefit (deficiencies) related to restricted stock awards	31							31
Stock-based compensation expense	2,717							2,717
Change in unfunded SERP liability, net of taxes	(1,485)				(1,485)
Net earnings	8,603	1,492	7,111	8,603
Balance at Dec. 31, 2014	224,273			213,409	(11,948)	217	969	21,626
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on Class A common stock	(522)			(522)
Cash dividends declared on Class B common stock	(2,713)			(2,713)
Issuance of restricted common stock	0						8	(8)
Forfeiture of restricted common stock	0						(7)	7
Foreign currency translation adjustment	(9,954)				(9,954)
Unrealized holding gains on marketable securities arising during the year net of taxes	5				5
Reclassification adjustment for gain (loss) on sale of marketable securities included in net earnings, net of tax of $-, $- and ($37)	0
Increase (Reduction) in APIC pool associated with tax benefit (deficiencies) related to restricted stock awards	0							0
Stock-based compensation expense	2,815							2,815
Change in unfunded SERP liability, net of taxes	21				21
Net earnings	19,197	$ 3,331	$ 15,866	19,197
Balance at Dec. 31, 2015	$ 233,122			$ 229,371	$ (21,876)	$ 217	$ 970	$ 24,440