Stockholders' Equity (Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	$ 3,892,045	$ 3,561,931
Net income	144,710	128,936
Pension and other post- retirement benefits liability	357	206
Foreign currency translation adjustments	20,551	22,805
Other	(75)	15,618
Shares issued—stock- based compensation	1,354	22
Stock-based compensation, net of tax on stock options exercised	3,009	2,569
Dividends declared	(24,656)	(23,700)
Distributions to noncontrolling interests	(4,463)	(3,985)
Amount, ending balance	4,032,832	3,704,402
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	1,347	1,347
Shares issued—stock- based compensation	0	0
Amount, ending balance	1,347	1,347
Common Stock, Held in Treasury [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	(319,339)	(258,312)
Shares issued—stock- based compensation	2,943	1,853
Amount, ending balance	(316,396)	(256,459)
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	550,641	542,148
Shares issued—stock- based compensation	(1,589)	(1,831)
Stock-based compensation, net of tax on stock options exercised	3,009	2,569
Amount, ending balance	552,061	542,886
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	3,412,286	3,109,987
Net income	138,190	123,128
Dividends declared	(24,656)	(23,700)
Amount, ending balance	3,525,820	3,209,415
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	(121,306)	(129,292)
Pension and other post- retirement benefits liability	401	206
Foreign currency translation adjustments	17,344	22,805
Other	(75)	15,618
Amount, ending balance	(103,636)	(90,663)
Noncontrolling Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Amount, beginning balance	368,416	296,053
Net income	6,520	5,808
Pension and other post- retirement benefits liability	(44)
Foreign currency translation adjustments	3,207
Distributions to noncontrolling interests	(4,463)	(3,985)
Amount, ending balance	$ 373,636	$ 297,876