Condensed Consolidated Statements Of Equity (USD $) In Thousands		Total	Common Stock [Member]	Capital Surplus [Member]	Accumulated Other Comprehensive (Loss) Income [Member]		Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2012		$ 1,357,179	$ 680	$ 416,104	$ (81,040)	[1]	$ 1,022,239	$ (11,903)	$ 11,099
Net income including noncontrolling interests		30,718					30,167		551
Other comprehensive income		480			480	[1]
Common stock issued under share-based compensation plans	[2]	1,222	2	1,179				41
Common stock issued under employee stock purchase plan		671		671
Distributions to noncontrolling interests		(1,050)							(1,050)
Share-based compensation expense		2,265		2,265
Balance at Mar. 31, 2013		1,391,485	682	420,219	(80,560)	[1]	1,052,406	(11,862)	10,600
Balance at Dec. 31, 2013		1,479,626	676	408,083	(65,777)	[1]	1,133,873	(10,590)	13,361
Net income including noncontrolling interests		41,842					41,261		581
Other comprehensive income		445			445	[1]
Common stock issued under share-based compensation plans	[2]	7,390	4	7,098				288
Common stock issued under employee stock purchase plan		866		866
Common stock dividends		(5,353)					(5,353)
Distributions to noncontrolling interests		(900)							(900)
Share-based compensation expense		2,598		2,598
Balance at Mar. 31, 2014		$ 1,526,514	$ 680	$ 418,645	$ (65,332)	[1]	$ 1,169,781	$ (10,302)	$ 13,042

[1] Represents cumulative foreign currency translation adjustments and post retirement liability adjustments.

[2] Includes the tax benefit associated with share-based compensation of $4.9 million and $0.4 million for the three months ended March 31, 2014 and 2013, respectively.