Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2017	20,745,041				1,480,101
Balance at Dec. 31, 2017	$ 207	$ 93,127	$ 28,333	$ (2,289)	$ (9,608)	$ 109,770
Net income			3,853			3,853
Other comprehensive income				283		283
Issuance of common stock for stock options exercised (in shares)	34,826
Issuance of common stock for stock options exercised	$ 1	292				293
Stock-based compensation expense		621				621
Repurchase of common stock at cost
Common stock dividend accrued			(1,350)			(1,350)
Balance (in shares) at Mar. 31, 2018	20,779,867				1,480,101
Balance at Mar. 31, 2018	$ 208	94,040	30,836	(2,006)	$ (9,608)	113,470
Balance (in shares) at Dec. 31, 2017	20,745,041				1,480,101
Balance at Dec. 31, 2017	$ 207	93,127	28,333	(2,289)	$ (9,608)	109,770
Net income						16,918
Other comprehensive income						(1,193)
Balance (in shares) at Sep. 30, 2018	21,080,465				1,498,603
Balance at Sep. 30, 2018	$ 211	97,727	41,178	(3,482)	$ (10,287)	125,347
Balance (in shares) at Mar. 31, 2018	20,779,867				1,480,101
Balance at Mar. 31, 2018	$ 208	94,040	30,836	(2,006)	$ (9,608)	113,470
Net income			8,751			8,751
Other comprehensive income				(1,201)		(1,201)
Issuance of common stock for stock options exercised (in shares)	56,215
Issuance of common stock for stock options exercised		446				446
Vested restricted stock units (in shares)	765
Vested restricted stock units
Stock-based compensation expense		636				636
Repurchase of common stock at cost (in shares)					149
Repurchase of common stock at cost					$ (5)	(5)
Common stock dividend accrued			(1,353)			(1,353)
Balance (in shares) at Jun. 30, 2018	20,836,847				1,480,250
Balance at Jun. 30, 2018	$ 208	95,122	38,234	(3,207)	$ (9,613)	120,744
Net income			4,314			4,314
Other comprehensive income				(275)		(275)
Issuance of common stock for stock options exercised (in shares)	192,487
Issuance of common stock for stock options exercised	$ 3	2,068				2,071
Vested restricted stock units (in shares)	51,131
Vested restricted stock units
Stock-based compensation expense		537				537
Repurchase of common stock at cost (in shares)					18,353
Repurchase of common stock at cost					$ (674)	(674)
Common stock dividend accrued			(1,370)			(1,370)
Balance (in shares) at Sep. 30, 2018	21,080,465				1,498,603
Balance at Sep. 30, 2018	$ 211	97,727	41,178	(3,482)	$ (10,287)	125,347
Balance (in shares) at Dec. 31, 2018	21,110,224				1,501,511
Balance at Dec. 31, 2018	$ 211	98,442	45,831	(3,900)	$ (10,349)	130,235
Net income			3,513			3,513
Other comprehensive income				(192)		(192)
Issuance of common stock for stock options exercised (in shares)	61,419
Issuance of common stock for stock options exercised	$ 1	478				479
Vested restricted stock units (in shares)	2,026
Vested restricted stock units
Stock-based compensation expense		746				746
Repurchase of common stock at cost (in shares)					926
Repurchase of common stock at cost					$ (21)	(21)
Common stock dividend accrued			(1,672)			(1,672)
Balance (in shares) at Mar. 31, 2019	21,173,669				1,502,437
Balance at Mar. 31, 2019	$ 212	99,666	47,672	(4,092)	$ (10,370)	133,088
Balance (in shares) at Dec. 31, 2018	21,110,224				1,501,511
Balance at Dec. 31, 2018	$ 211	98,442	45,831	(3,900)	$ (10,349)	130,235
Net income						13,321
Other comprehensive income						(994)
Balance (in shares) at Sep. 30, 2019	21,495,306				1,515,378
Balance at Sep. 30, 2019	$ 215	103,673	54,117	(4,894)	$ (10,795)	142,316
Balance (in shares) at Mar. 31, 2019	21,173,669				1,502,437
Balance at Mar. 31, 2019	$ 212	99,666	47,672	(4,092)	$ (10,370)	133,088
Net income			4,624			4,624
Other comprehensive income				274		274
Issuance of common stock for stock options exercised (in shares)	77,032
Issuance of common stock for stock options exercised	$ 1	530				531
Vested restricted stock units (in shares)	171
Vested restricted stock units
Stock-based compensation expense		694				694
Repurchase of common stock at cost (in shares)					1,008
Repurchase of common stock at cost					$ (2)	(2)
Common stock dividend accrued			(1,672)			(1,672)
Balance (in shares) at Jun. 30, 2019	21,250,872				1,503,445
Balance at Jun. 30, 2019	$ 213	100,890	50,624	(3,818)	$ (10,372)	137,537
Net income			5,184			5,184
Other comprehensive income				(1,076)		(1,076)
Issuance of common stock for stock options exercised (in shares)	208,821
Issuance of common stock for stock options exercised	$ 2	2,128				2,130
Vested restricted stock units (in shares)	35,613
Vested restricted stock units
Stock-based compensation expense		655				655
Repurchase of common stock at cost (in shares)					11,933
Repurchase of common stock at cost					$ (423)	(423)
Common stock dividend accrued			(1,691)			(1,691)
Balance (in shares) at Sep. 30, 2019	21,495,306				1,515,378
Balance at Sep. 30, 2019	$ 215	$ 103,673	$ 54,117	$ (4,894)	$ (10,795)	$ 142,316