Consolidated Statement Of Equity (USD $) In Thousands	Common Stock [Member]	Capital Excess Of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2014	$ 89,296	$ 758,145	$ 849,952	$ (42,838)	$ 788	$ 40	$ 1,655,383
Net income			48,545				48,545
Other comprehensive income, net of income tax of $41					75		75
Dividends			(29,176)				(29,176)
Repurchase of stock (140,984 shares)				(3,754)			(3,754)
Equity compensation plan (280,401 shares)	140	(140)
Exercise of stock options (170,270 shares)	85	2,767					2,852
Stock-based compensation		1,341	(118)				1,223
Employee stock plan tax benefits		1,409					1,409
Other		(263)					(263)
Balance at Mar. 31, 2015	$ 89,521	$ 763,259	$ 869,203	$ (46,592)	$ 863	$ 40	$ 1,676,294