CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock	Additional Paid-In Capital Cumulative Effect, Period of Adoption, Adjusted Balance	Additional Paid-In Capital	Accumulated Surplus Cumulative Effect, Period of Adoption, Adjustment	Accumulated Surplus Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Surplus	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Income (Loss)	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Total
BALANCE at Dec. 31, 2017		$ 114		$ 150,699			$ 55,256		$ (3,293)			$ 202,776
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Prior period accounting reclassification							552		(552)
Components of comprehensive income:
Net income							33,746					33,746
Foreign currency translation adjustments									(965)			(965)
COMPREHENSIVE INCOME							34,298		(1,517)			32,781
Issuance of common stock to non-employee directors				150								150
Exercise of stock options				56								56
Dividends paid							(8,200)					(8,200)
BALANCE at Dec. 31, 2018	$ 114	114	$ 150,905	150,905	$ 4	$ 81,358	81,354	$ (4,810)	(4,810)	$ 4	$ 227,567	227,563
Components of comprehensive income:
Net income							39,111					39,111
Foreign currency translation adjustments									(693)			(693)
COMPREHENSIVE INCOME							39,111		(693)			38,418
Issuance of common stock to non-employee directors				150								150
Dividends paid							(8,208)					(8,208)
BALANCE at Dec. 31, 2019		114		151,055			112,261		(5,503)			257,927
Components of comprehensive income:
Net income							29,830					29,830
Foreign currency translation adjustments									2,714			2,714
COMPREHENSIVE INCOME							29,830		2,714			32,544
Issuance of common stock to non-employee directors				194								194
Dividends paid							(8,212)					(8,212)
BALANCE at Dec. 31, 2020		$ 114		$ 151,249			$ 133,879		$ (2,789)			$ 282,453