Consolidated Statements Of Equity - USD ($) $ in Thousands		Total	Common Stock	Capital Surplus	Accumulated Other Comprehensive (Loss) Income	[1]	Retained Earnings	Treasury Stock	Noncontrolling Interests
Balance at Dec. 31, 2014		$ 1,429,387	$ 636	$ 227,885	$ (83,197)		$ 1,280,991	$ (10,302)	$ 13,374
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including noncontrolling interests		172,507					172,286		221
Other comprehensive income (loss)		6,244			6,244
Common stock issued under share-based compensation plans	[2]	5,433	5	5,428
Tax withholding for common stock issued under share-based compensation plans		(3,866)		(3,866)
Common stock issued under employee stock purchase plan		4,223		4,223
Common stock dividends		(20,095)					(20,297)
Common stock dividends, accrued dividend shares				202
Repurchase of common stock		(112,328)	(24)	(112,304)
Distributions to noncontrolling interests		(10,250)							(10,250)
Share-based compensation expense		8,801		8,801
Balance at Dec. 31, 2015		1,480,056	617	130,369	(76,953)		1,432,980	(10,302)	3,345
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including noncontrolling interests		182,153					181,935		218
Other comprehensive income (loss)		(24,750)			(24,750)
Common stock issued under share-based compensation plans	[3]	1,724	4	729			991
Tax withholding for common stock issued under share-based compensation plans		(4,225)		(4,225)
Common stock issued under employee stock purchase plan		4,814		4,814
Common stock dividends		(19,454)					(19,637)
Common stock dividends, accrued dividend shares				183
Repurchase of common stock		(88,568)	(15)	(88,553)
Distributions to noncontrolling interests		(2,710)							(2,710)
Share-based compensation expense		8,902		8,902
Balance at Dec. 31, 2016		1,537,942	606	52,219	(101,703)		1,596,269	(10,302)	853
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income including noncontrolling interests		227,193					227,196		(3)
Other comprehensive income (loss)		7,503			7,503
Common stock issued under share-based compensation plans		1	2	(1)
Tax withholding for common stock issued under share-based compensation plans		(3,462)		(3,462)
Common stock issued under employee stock purchase plan		4,793	1	4,792
Common stock dividends		(18,971)					(19,135)
Common stock dividends, accrued dividend shares				164
Repurchase of common stock		(90,821)	(10)	(55,646)			(7,774)	(27,391)
Distributions to noncontrolling interests		0							0
Share-based compensation expense		9,939		9,939
Balance at Dec. 31, 2017		$ 1,674,117	$ 599	$ 8,005	$ (94,200)		$ 1,796,556	$ (37,693)	$ 850

[1] As of December 31, 2017, represents cumulative foreign currency translation and post retirement liability adjustments of $0.5 million and $(94.7) million, respectively. As of December 31, 2016, represents cumulative foreign currency translation and post retirement liability adjustments of $2.1 million and $(103.8) million, respectively. As of December 31, 2015, represents cumulative foreign currency translation and post retirement liability adjustments of $3.5 million and $(80.5) million, respectively.

[2] Includes the tax benefit associated with share-based compensation of $1.6 million in 2015.

[3] Includes a $1.0 million adjustment to retained earnings to recognize net operating loss carryforwards attributable to excess tax benefits on stock compensation upon the adoption of Accounting Standards Update No. 2016-09.