Consolidated Statements Of Changes In Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock	Non-controlling Interest
Beginning balance at Dec. 31, 2014	$ 5,181.3	$ 1.5	$ 3,131.2	$ 4,809.3	$ 555.8	$ (3,316.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan exercises	(17.5)	0.0	(17.5)
Stock plan compensation expense	38.8		38.8
Change in tax benefit from share-based payment arrangements	(4.1)		(4.1)
Dividends	(94.2)			(94.2)
Acquisition of common stock	(284.7)					(284.7)
Net income	141.6			141.6
Other comprehensive income (loss)	(437.2)				(437.2)
Ending balance at Dec. 31, 2015	4,524.0	1.5	3,148.4	4,856.7	118.6	(3,601.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan exercises	(19.8)	0.0	(19.8)
Stock plan compensation expense	41.7		41.7
Change in tax benefit from share-based payment arrangements	5.6		5.6
Dividends	(125.4)			(125.4)
Acquisition of common stock	(869.4)					(869.4)
Net income	565.4			565.4
Other comprehensive income (loss)	(24.0)				(24.0)
Ending balance at Dec. 31, 2016	4,098.1	1.5	3,175.9	5,296.7	94.6	(4,470.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan exercises	(13.5)	0.0	(13.5)
Stock plan compensation expense	35.5		35.5
Dividends	(119.0)			(119.0)
Acquisition of common stock	(389.5)			0.0		(389.5)
Change in equity of non-controlling interest	10.9						$ 10.9
Net income	519.6			519.6
Other comprehensive income (loss)	139.4				139.4
Ending balance at Dec. 31, 2017	$ 4,281.5	$ 1.5	$ 3,197.9	$ 5,697.3	$ 234.0	$ (4,860.1)	$ 10.9