CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid- In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Change in accounting principal				$ (2,018)		$ (2,018)
Balance (Scenario, Previously Reported [Member]) at Dec. 31, 2017	$ 12	$ 4,967	$ (160)	103,762		108,581
Balance at Dec. 31, 2017	$ 12	4,967	(160)	101,744		106,563
Balance (in shares) (Scenario, Previously Reported [Member]) at Dec. 31, 2017	12,103
Balance (in shares) at Dec. 31, 2017	12,103
Net income				12,222		12,222
Share-based compensation		805				805
Share-based compensation (in shares)	16
Options exercised by executives and directors		62				62
Options exercised by executives and directors (in shares)	14
Net shares repurchased for employee taxes		(215)				(215)
Net shares repurchased for employee taxes, (in shares)	(3)
Treasury stock from cashless options		750			$ (750)
Treasury stock from cashless options, (in shares)	9
Other comprehensive income (loss)			(84)			(84)
Cash dividends declared to stockholders				(5,723)		(5,723)
Balance at Mar. 31, 2018	$ 12	6,369	(244)	108,243	(750)	113,630
Balance (in shares) at Mar. 31, 2018	12,139
Balance at Dec. 31, 2018	$ 12	8,802	(173)	131,344	(30,879)	109,106
Balance (in shares) at Dec. 31, 2018	12,117
Net income				20,750		20,750
Share-based compensation		990				990
Options exercised by executives and directors		269				269
Options exercised by executives and directors (in shares)	10
Net shares repurchased for employee taxes		(256)				(256)
Net shares repurchased for employee taxes, (in shares)	(1)
Other comprehensive income (loss)			127			127
Cash dividends declared to stockholders				(8,918)		(8,918)
Balance at Mar. 31, 2019	$ 12	$ 9,805	$ (46)	$ 143,176	$ (30,879)	$ 122,068
Balance (in shares) at Mar. 31, 2019	12,126