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, 2008	$ 7,441	$ 1,735	$ 319,362	$ 536	$ (18,469)	$ 310,605
Balance, shares at Dec. 31, 2008	6,848
Net earnings			62,576			62,576
Unrealized gain/loss on available-for-sale securities, net of tax				107		107
Total comprehensive income						62,683
Dividends paid			(38,008)			(38,008)
Other		302			290	592
Other, shares	10
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 gain/loss on available-for-sale securities, net of tax				(514)		(514)
Total comprehensive income						63,017
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 gain/loss on available-for-sale securities, net of tax				(57)		(57)
Total comprehensive income						47,911
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