Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 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]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock, Common Class A [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock, Common Class B [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [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, 2018													$ 463	$ (463)	$ 0	$ 0	$ 0	$ 0	$ 168,695	$ (24,838)	$ 217	$ 1,009	$ 31,387	$ 176,470
Net earnings (loss)																			1,131	0	0	0	0	1,131
Cash dividends declared on common stock	$ (130)	$ 0	$ 0	$ 0	$ 0	$ (130)	$ (708)	$ 0	$ 0	$ 0	$ 0	$ (708)
Forfeiture of restricted common stock																			0	0	0	(1)		0
Forfeiture of restricted common stock																							1
Foreign currency translation adjustment, net of taxes																			0	540	0	0	0	540
Stock-based compensation expense																			0	0	0	0	813	813
Change in unfunded SERP liability, net of taxes																			0	37	0	0	0	37
Balance at Mar. 31, 2019																			169,451	(24,724)	217	1,008	32,201	178,153
Balance at Dec. 31, 2018													$ 463	$ (463)	$ 0	$ 0	$ 0	$ 0	168,695	(24,838)	217	1,009	31,387	176,470
Net earnings (loss)						(442)						(1,949)												(2,391)
Cash dividends declared on common stock						(392)						(2,124)
Foreign currency translation adjustment, net of taxes																								(2,854)
Change in unfunded SERP liability, net of taxes																								111
Balance at Sep. 30, 2019																			164,252	(28,045)	214	1,013	33,206	170,640
Balance at Mar. 31, 2019																			169,451	(24,724)	217	1,008	32,201	178,153
Net earnings (loss)																			2,967	0	0	0	0	2,967
Cash dividends declared on common stock	(131)	0	0	0	0	(131)	(704)	0	0	0	0	(704)
Forfeiture of restricted common stock																			0	0	0	(1)		0
Forfeiture of restricted common stock																							1
Foreign currency translation adjustment, net of taxes																			0	(834)	0	0	0	(834)
Stock-based compensation expense																			0	0	0	0	788	788
Change in unfunded SERP liability, net of taxes																			0	37	0	0	0	37
Issuance of restricted common stock																			0	0	0	7	(7)	0
Balance at Jun. 30, 2019																			171,583	(25,521)	217	1,014	32,983	180,276
Net earnings (loss)						(1,112)						(5,378)							(6,490)	0	0	0	0	(6,490)
Cash dividends declared on common stock	(131)	0	0	0	0	(131)	(710)	0	0	0	0	(710)
Forfeiture of restricted common stock																			0	0	0	(1)		0
Forfeiture of restricted common stock																							1
Foreign currency translation adjustment, net of taxes																			0	(2,561)	0	0	0	(2,561)
Stock-based compensation expense																			0	0	0	0	667	667
Change in unfunded SERP liability, net of taxes																			0	37	0	0	0	37
Repurchase of Class A common stock																			0	0	(3)	0	(445)	(448)
Balance at Sep. 30, 2019																			164,252	(28,045)	214	1,013	33,206	170,640
Balance at Dec. 31, 2019																			157,063	(24,065)	214	1,013	33,826	168,051
Net earnings (loss)																			(3,804)	0	0	0	0	(3,804)
Cash dividends declared on common stock	(130)	0	0	0	0	(130)	(709)	0	0	0	0	(709)
Forfeiture of restricted common stock																			0	0	0	(1)		0
Forfeiture of restricted common stock																							1
Foreign currency translation adjustment, net of taxes																			0	(2,245)	0	0	0	(2,245)
Stock-based compensation expense																			0	0	0	0	603	603
Change in unfunded SERP liability, net of taxes																			0	66	0	0	0	66
Balance at Mar. 31, 2020																			152,420	(26,244)	214	1,012	34,430	161,832
Balance at Dec. 31, 2019																			157,063	(24,065)	214	1,013	33,826	168,051
Net earnings (loss)						1,512						7,732												9,244
Cash dividends declared on common stock						(388)						(2,133)
Foreign currency translation adjustment, net of taxes																								2,019
Change in unfunded SERP liability, net of taxes																								198
Balance at Sep. 30, 2020																			163,786	(21,848)	214	1,022	35,597	178,771
Balance at Mar. 31, 2020																			152,420	(26,244)	214	1,012	34,430	161,832
Net earnings (loss)																			5,573	0	0	0	0	5,573
Cash dividends declared on common stock	(129)	0	0	0	0	(129)	(707)	0	0	0	0	(707)
Forfeiture of restricted common stock																			0	0	0	11		0
Forfeiture of restricted common stock																							(11)
Foreign currency translation adjustment, net of taxes																			0	676	0	0	0	676
Stock-based compensation expense																			0	0	0	0	617	617
Change in unfunded SERP liability, net of taxes																			0	66	0	0	0	66
Balance at Jun. 30, 2020																			157,157	(25,502)	214	1,023	35,036	167,928
Net earnings (loss)						1,233						6,242							7,475	0	0	0	0	7,475
Cash dividends declared on common stock	$ (129)	$ 0	$ 0	$ 0	$ 0	$ (129)	$ (717)	$ 0	$ 0	$ 0	$ 0	$ (717)
Forfeiture of restricted common stock																			0	0	0	(1)		0
Forfeiture of restricted common stock																							1
Foreign currency translation adjustment, net of taxes																			0	3,588	0	0	0	3,588
Stock-based compensation expense																			0	0	0	0	560	560
Change in unfunded SERP liability, net of taxes																			0	66	0	0	0	66
Balance at Sep. 30, 2020																			$ 163,786	$ (21,848)	$ 214	$ 1,022	$ 35,597	$ 178,771