Consolidated Statements Of Changes In Equity (USD $) In Thousands	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-Controlling Interest [Member]	Total
Balance at Dec. 31, 2010	$ 433,942	$ 971,293	$ 555,778	$ (2,371)	$ 63,345	$ 1,477	$ 2,023,464
Net income			60,453			497	60,950
Other comprehensive income (loss)					(2,211)		(2,211)
Distributions to non-controlling interest						(206)	(206)
Purchase of treasury stock				(4,311)			(4,311)
Issuance of stock under purchase and equity compensation plans	1,136	3,687		6,062			10,885
Net tax benefit related to equity compensation plans		717					717
Stock-based compensation		1,256					1,256
Issuance of nonvested stock awards	965	(852)		(113)
Cash dividends			(20,054)				(20,054)
Balance at Mar. 31, 2011	436,043	976,101	596,177	(733)	61,134	1,768	2,070,490
Balance at Dec. 31, 2011	446,387	1,042,065	575,419	(8,362)	110,538	4,314	2,170,361
Net income			65,799			1,015	66,814
Other comprehensive income (loss)					7,518		7,518
Distributions to non-controlling interest						(1,459)	(1,459)
Purchase of treasury stock				(31,600)			(31,600)
Issuance of stock under purchase and equity compensation plans		(3,065)		9,019			5,954
Net tax benefit related to equity compensation plans		649					649
Stock-based compensation		1,407					1,407
Issuance of nonvested stock awards		(8,071)		8,071
Cash dividends			(20,438)				(20,438)
Balance at Mar. 31, 2012	$ 446,387	$ 1,032,985	$ 620,780	$ (22,872)	$ 118,056	$ 3,870	$ 2,199,206