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
Balance at Dec. 31, 2009	$ 7,441	$ 2,037			$ 343,930	$ 643	$ (18,179)			$ 335,872
Balance, shares at Dec. 31, 2009	6,858
Net earnings					63,531					63,531
Unrealized loss on available-for-sale securities, net of tax						(514)				(514)
Dividends paid					(55,889)					(55,889)
Other		701			(1)		237			937
Other, shares	7
Balance at Dec. 31, 2010	7,441	2,738			351,571	129	(17,942)			343,937
Balance, shares at Dec. 31, 2010	6,865
Net earnings					47,968					47,968
Unrealized loss on available-for-sale securities, net of tax						(57)				(57)
Dividends paid					(56,665)					(56,665)
Other		801			(1)		307			1,107
Other, shares	10
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, net of tax						(19)				(19)
Dividends paid			(41,292)	(44,814)				(41,292)	(44,814)
Other		933			1		597			1,531
Other, shares	19
Balance at Dec. 31, 2012	$ 7,441	$ 4,472			$ 295,643	$ 53	$ (17,038)			$ 290,571
Balance, shares at Dec. 31, 2012	6,894