CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Class A [Member]	Class B [Member]	Retained Earnings [Member]	Retained Earnings [Member] Class A [Member]	Retained Earnings [Member] Class B [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, 2013	$ 228,702			$ 207,993			$ 645	$ 217	$ 933	$ 18,914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on common stock		$ (522)	$ (2,665)		$ (522)	$ (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
Increase in APIC pool associated with tax benefits 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 (loss) 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 common stock		(522)	(2,713)		(522)	(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
Stock-based compensation expense	2,815									2,815
Change in unfunded SERP liability, net of taxes	21						21
Net (loss) earnings	19,197	3,331	15,866	19,197
Balance at Dec. 31, 2015	233,122			229,371			(21,876)	217	970	24,440
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared on common stock		(522)	(2,728)		$ (522)	$ (2,728)
Issuance of restricted common stock	0								18	(18)
Forfeiture of restricted common stock	0								(3)	3
Foreign currency translation adjustment	(9,671)						(9,671)
Unrealized holding gains on marketable securities arising during the year net of taxes	(10)						(10)
Stock-based compensation expense	2,817									2,817
Change in unfunded SERP liability, net of taxes	260						260
Net (loss) earnings	(64,834)	$ (11,408)	$ (53,426)	(64,834)
Balance at Dec. 31, 2016	$ 158,434			$ 161,287			$ (31,297)	$ 217	$ 985	$ 27,242