Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	AOCI Attributable to Parent [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2016	43,749,970
Balance at Dec. 31, 2016	$ 4	$ 3,540	$ 281,087	$ 48,182	$ 332,813
Dividends				(10,498)	(10,498)
Stock-based compensation			998		998
Minimum tax withholdings on options and awards			(121)		(121)
Other comprehensive income		4,893			4,893
Net income				23,511	23,511
Balance (in shares) at Dec. 31, 2017	43,741,670
Balance at Dec. 31, 2017	$ 4	8,433	281,964	61,195	351,596
Dividends				(10,498)	(10,498)
Stock-based compensation			357		357
Minimum tax withholdings on options and awards			(176)		(176)
Other comprehensive income		(180)			(180)
Net income				53,158	53,158
Prior period adjustment: Change in accounting principles at Dec. 31, 2017		(8,273)		3,094	(5,179)
Balance - As adjusted (in shares) at Dec. 31, 2017	43,741,670
Balance - As adjusted at Dec. 31, 2017	$ 4	160	281,964	64,289	346,417
Stock-based compensation (in shares)	1,573
Balance (in shares) at Dec. 31, 2018	43,743,243
Balance at Dec. 31, 2018	$ 4	(20)	282,145	106,949	389,078
Dividends				(10,498)	(10,498)
Stock-based compensation			21		21
Other comprehensive income		316			316
Net income				88,181	88,181
Balance (in shares) at Dec. 31, 2019	43,743,243
Balance at Dec. 31, 2019	$ 4	$ 296	$ 282,166	$ 184,632	$ 467,098