Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Income
Balance at beginning of year (in shares) at Dec. 31, 2019		9,043,771
Balance at beginning of year at Dec. 31, 2019	$ 108,001	$ 9,190	$ 18,077	$ 86,496	$ (5,761)	$ (1)
Net income	12,533			12,533
Adjustment for foreign currency translation	(2,494)					(2,494)
Stock-based compensation	451		451
Shares repurchased held in treasury (in shares)		(47,504)
Shares repurchased held in treasury	(1,756)				(1,756)
Balance at end of period (in shares) at Mar. 31, 2020		8,996,267
Balance at end of period at Mar. 31, 2020	116,735	$ 9,190	18,528	99,029	(7,517)	(2,495)
Balance at beginning of year (in shares) at Dec. 31, 2019		9,043,771
Balance at beginning of year at Dec. 31, 2019	108,001	$ 9,190	18,077	86,496	(5,761)	(1)
Net income	13,152
Adjustment for foreign currency translation	(1,316)
Balance at end of period (in shares) at Jun. 30, 2020		9,007,411
Balance at end of period at Jun. 30, 2020	119,044	$ 9,201	19,029	99,648	(7,517)	(1,317)
Balance at beginning of year (in shares) at Mar. 31, 2020		8,996,267
Balance at beginning of year at Mar. 31, 2020	116,735	$ 9,190	18,528	99,029	(7,517)	(2,495)
Net income	619			619
Adjustment for foreign currency translation	1,178					1,178
Stock-based compensation	498		498
Shares issued (in shares)		11,144
Shares issued	14	$ 11	3
Balance at end of period (in shares) at Jun. 30, 2020		9,007,411
Balance at end of period at Jun. 30, 2020	$ 119,044	$ 9,201	19,029	99,648	(7,517)	(1,317)
Balance at beginning of year (in shares) at Dec. 31, 2020	9,287,625	9,061,039
Balance at beginning of year at Dec. 31, 2020	$ 122,422	$ 9,288	19,841	101,609	(9,015)	699
Net income	3,596			3,596
Adjustment for foreign currency translation	631					631
Stock-based compensation	422		422
Shares issued (in shares)		5,776
Shares issued	0	$ 5	(5)
Shares repurchased held in treasury (in shares)		(268)
Shares repurchased held in treasury	(13)				(13)
Balance at end of period (in shares) at Mar. 31, 2021		9,066,547
Balance at end of period at Mar. 31, 2021	$ 127,058	$ 9,293	20,258	105,205	(9,028)	1,330
Balance at beginning of year (in shares) at Dec. 31, 2020	9,287,625	9,061,039
Balance at beginning of year at Dec. 31, 2020	$ 122,422	$ 9,288	19,841	101,609	(9,015)	699
Net income	6,531
Adjustment for foreign currency translation	$ 985
Balance at end of period (in shares) at Jun. 30, 2021	9,304,366
Balance at end of period at Jun. 30, 2021	$ 130,898
Balance at beginning of year (in shares) at Mar. 31, 2021		9,066,547
Balance at beginning of year at Mar. 31, 2021	127,058	$ 9,293	20,258	105,205	$ (9,028)	$ 1,330
Net income	2,935			$ 2,935
Adjustment for foreign currency translation	354						$ 354
Stock-based compensation	$ 551		551
Shares issued (in shares)	10,965
Shares issued	$ 0	$ 11	$ (11)
Balance at end of period (in shares) at Jun. 30, 2021	9,304,366
Balance at end of period at Jun. 30, 2021	$ 130,898