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, 2013	$ 7,441	$ 4,998	$ 336,895	$ 8	$ (16,791)	$ 332,551
Balance, shares at Dec. 31, 2013	6,902,000
Net earnings			26,477			26,477
Unrealized loss on available-for-sale securities				(11)		(11)
Dividends paid			(34,954)			(34,954)
Other		908	(1)		473	1,380
Other, shares	15,000
Balance at Dec. 31, 2014	$ 7,441	5,906	328,417	(3)	(16,318)	325,443
Balance, shares at Dec. 31, 2014	6,917,000
Net earnings			40,496			40,496
Unrealized loss on available-for-sale securities				(6)		(6)
Dividends paid			(28,114)			(28,114)
Other		869			566	1,435
Other, shares	18,000
Balance at Dec. 31, 2015	$ 7,441	6,775	340,799	(9)	(15,752)	$ 339,254
Balance, shares at Dec. 31, 2015	6,935,000					6,935,471
Net earnings			44,564			$ 44,564
Unrealized loss on available-for-sale securities				(38)		(38)
Dividends paid			(35,161)			(35,161)
Other		1,138	1		478	1,617
Other, shares	16,000
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					6,950,786