Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Class A [Member] Retained Earnings [Member]	Common Class A [Member] AOCI Attributable to Parent [Member]	Common Class A [Member] Common Stock, Common Class A [Member]	Common Class A [Member] Common Stock, Common Class B [Member]	Common Class A [Member] Additional Paid-in Capital [Member]	Common Class A [Member]	Common Class B [Member] Retained Earnings [Member]	Common Class B [Member] AOCI Attributable to Parent [Member]	Common Class B [Member] Common Stock, Common Class A [Member]	Common Class B [Member] Common Stock, Common Class B [Member]	Common Class B [Member] Additional Paid-in Capital [Member]	Common Class B [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Common Stock, Common Class A [Member]	Common Stock, Common Class B [Member]	Additional Paid-in Capital [Member]	Total
Balance at Dec. 31, 2017													$ 147,807	$ (19,625)	$ 217	$ 986	$ 28,575	$ 157,960
Net (loss) earnings						$ 3,521						$ 17,188	20,709					20,709
Cash dividends declared on common stock	$ (522)					(522)	$ (2,796)					(2,796)
Issuance of restricted common stock																26	(26)
Forfeiture of restricted common stock																(3)
Forfeiture of restricted common stock, APIC																	3
Foreign currency translation adjustment, net of taxes														(6,098)				(6,098)
Unrealized holding losses on marketable securities arising during the period, net of taxes of ($0) and ($85)														(133)				(133)
Stock-based compensation expense																	2,835	2,835
Change in unfunded SERP liability, net of taxes														1,018				1,018
Balance at Dec. 31, 2018													168,695	(24,838)	217	1,009	31,387	176,470
Effect of adoption of ASU													3,497					3,497
Net (loss) earnings						(1,531)						(7,212)	(8,743)					(8,743)
Cash dividends declared on common stock	$ (518)					$ (518)	$ (2,834)					$ (2,834)
Forfeiture of restricted common stock																(3)
Forfeiture of restricted common stock, APIC																	3
Foreign currency translation adjustment, net of taxes														2,603				2,603
Unrealized holding losses on marketable securities arising during the period, net of taxes of ($0) and ($85)
Stock-based compensation expense																	2,888	2,888
Change in unfunded SERP liability, net of taxes														(1,367)				(1,367)
Issuance of stock awards																7
Issuance of stock awards, APIC																	(7)
Repurchase of Class A common stock															(3)		(445)	(448)
Balance at Dec. 31, 2019													157,063	(24,065)	214	1,013	33,826	168,051
Effect of adoption of ASU													$ 463	$ (463)