Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2017	7,280			30
Balance at Dec. 31, 2017	$ 73	$ 26,664	$ 97,562	$ (587)	$ 123,712
Share-based compensation (in shares)	16
Share-based compensation		237			237
Exercise of stock options net of shares presented for exercise (in shares)	30
Exercise of stock options net of shares presented for exercise		367			367
Net share settlement of restricted stock units and stock option tax withholding (in shares)	(5)
Net share settlement of restricted stock units and stock option tax withholding		(144)			(144)
Net income			1,777		1,777
Excess tax benefits on share-based compensation - adjustment		167			167
Adoption of ASC 606			(95)		(95)
Balance (in shares) at Mar. 31, 2018	7,321			30
Balance at Mar. 31, 2018	$ 73	27,291	99,244	$ (587)	126,021
Balance (in shares) at Dec. 31, 2017	7,280			30
Balance at Dec. 31, 2017	$ 73	26,664	97,562	$ (587)	123,712
Net income					5,767
Balance (in shares) at Jun. 30, 2018	7,359			30
Balance at Jun. 30, 2018	$ 74	28,341	103,258	$ (587)	131,086
Balance (in shares) at Mar. 31, 2018	7,321			30
Balance at Mar. 31, 2018	$ 73	27,291	99,244	$ (587)	126,021
Share-based compensation (in shares)	3
Share-based compensation	$ 1	453			454
Exercise of stock options net of shares presented for exercise (in shares)	35
Exercise of stock options net of shares presented for exercise		597			597
Net share settlement of restricted stock units and stock option tax withholding
Net income			3,990		3,990
Excess tax benefits on share-based compensation - adjustment
Adoption of ASC 606			24		24
Balance (in shares) at Jun. 30, 2018	7,359			30
Balance at Jun. 30, 2018	$ 74	28,341	103,258	$ (587)	131,086
Balance (in shares) at Dec. 31, 2018	7,385			30
Balance at Dec. 31, 2018	$ 74	29,168	111,802	$ (587)	140,457
Share-based compensation (in shares)	20
Share-based compensation		294			294
Exercise of stock options net of shares presented for exercise (in shares)	17
Exercise of stock options net of shares presented for exercise		285			285
Net share settlement of restricted stock units and stock option tax withholding (in shares)	(8)
Net share settlement of restricted stock units and stock option tax withholding		(271)			(271)
Net income			3,734		3,734
Balance (in shares) at Mar. 31, 2019	7,414			30
Balance at Mar. 31, 2019	$ 74	29,476	115,536	$ (587)	144,499
Balance (in shares) at Dec. 31, 2018	7,385			30
Balance at Dec. 31, 2018	$ 74	29,168	111,802	$ (587)	140,457
Net income					8,332
Balance (in shares) at Jun. 30, 2019	7,428			30
Balance at Jun. 30, 2019	$ 74	30,033	120,134	$ (587)	149,654
Balance (in shares) at Mar. 31, 2019	7,414			30
Balance at Mar. 31, 2019	$ 74	29,476	115,536	$ (587)	144,499
Share-based compensation		402			402
Exercise of stock options net of shares presented for exercise (in shares)	14
Exercise of stock options net of shares presented for exercise		155			155
Net share settlement of restricted stock units and stock option tax withholding
Net income			4,598		4,598
Balance (in shares) at Jun. 30, 2019	7,428			30
Balance at Jun. 30, 2019	$ 74	$ 30,033	$ 120,134	$ (587)	$ 149,654