Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2016	$ 7,441	$ 7,913	$ 350,203	$ (47)	$ (15,274)	$ 350,236
Balance, shares at Dec. 31, 2016	6,951,000
Net earnings			52,959			52,959
Unrealized gain (loss) on available-for-sale securities, net of tax				(39)		(39)
Dividends paid			(38,405)			(38,405)
Other		1,161			464	1,625
Other, shares	17,000
Balance at Dec. 31, 2017	$ 7,441	9,074	364,757	(86)	(14,810)	366,376
Balance, shares at Dec. 31, 2017	6,968,000
Net earnings			39,940			39,940
Unrealized gain (loss) on available-for-sale securities, net of tax				107		107
Dividends paid			(41,989)			(41,989)
Other		1,286	1		402	1,689
Other, shares	13,000
Balance at Dec. 31, 2018	$ 7,441	10,360	362,709	21	(14,408)	$ 366,123
Balance, shares at Dec. 31, 2018	6,981,000					6,981,080
Net earnings			42,220			$ 42,220
Unrealized gain (loss) on available-for-sale securities, net of tax				115		115
Dividends paid			(42,087)			(42,087)
Other		1,087			499	1,586
Other, shares	25,000
Balance at Dec. 31, 2019	$ 7,441	$ 11,447	$ 362,842	$ 136	$ (13,909)	$ 367,957
Balance, shares at Dec. 31, 2019	7,006,000					7,006,323