Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member] Quarter 1 Dividend Payment [Member]	Retained Earnings [Member] Quarter 4 Dividend Payment [Member]	Retained Earnings [Member]	Accumulated Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Quarter 1 Dividend Payment [Member]	Quarter 4 Dividend Payment [Member]	Total
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2011	$ 7,441	$ 3,539			$ 342,873	$ 72	$ (17,635)			$ 336,290
Balance, shares at Dec. 31, 2011	6,875
Net earnings					38,875					38,875
Unrealized loss on available-for-sale securities						(19)				(19)
Dividends paid			(41,292)	(44,814)				(41,292)	(44,814)
Other		933			1		597			1,531
Other, shares	19
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2012	7,441	4,472			295,643	53	(17,038)			290,571
Balance, shares at Dec. 31, 2012	6,894
Net earnings					41,252					41,252
Unrealized loss on available-for-sale securities						(45)				(45)
Other		526					247			773
Other, shares	8
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2013	7,441	4,998			336,895	8	(16,791)			332,551
Balance, shares at Dec. 31, 2013	6,902
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
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2014	$ 7,441	$ 5,906			$ 328,417	$ (3)	$ (16,318)			$ 325,443
Balance, shares at Dec. 31, 2014	6,917