Consolidated Statement Of Equity (USD $) In Thousands	Common Stock [Member]	Capital In Excess Of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2011	$ 69,762	$ 686,106	$ 508,334	$ (13,145)	$ 256	$ 504	$ 1,251,817
Net income			79,349			12	79,361
Other comprehensive loss net of income tax of $39					(69)		(69)
Dividends declared			(45,872)				(45,872)
Sale of stock (298,427 shares)	149	6,251		29			6,429
Repurchase of stock (50,227 shares)				(1,132)			(1,132)
Equity compensation plan (26,993 shares)	13	(13)
Exercise of stock options (473,351 shares)	237	7,636					7,873
Stock-based compensation		2,867	(72)				2,795
Employee stock plan tax benefits		1,481					1,481
Balance at Jun. 30, 2012	$ 70,161	$ 704,328	$ 541,739	$ (14,248)	$ 187	$ 516	$ 1,302,683