Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Minority Interests
Beginning balance at Dec. 31, 2015	$ 10,945.2		$ 2.0	$ 8,718.1	$ 2,524.0	$ (142.1)	$ (157.3)	$ 0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	294.5				294.5
Other comprehensive income, net of tax	37.9					37.9
Dividends paid	(92.2)				(92.2)
Amortization of restricted stock, stock option and performance shares expenses	17.5			38.2			(20.7)
Issuance of common stock — acquisition	0.1		0.1
Employee stock purchase plan	1.9			1.9
Ending balance at Sep. 30, 2016	11,204.9	$ 0.0	2.1	8,758.2	2,726.3	(104.2)	(178.0)	0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of Accounting Standard Update 2016-09				1.0	(1.0)
December 31, 2016	10,003.1	0.0	2.1	8,766.8	1,552.0	(140.1)	(178.1)	0.4
Beginning balance at Dec. 31, 2016	10,003.1	0.0	2.1	8,765.8	1,553.0	(140.1)	(178.1)	0.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	556.2				556.2
Other comprehensive income, net of tax	66.8					66.8
Dividends paid	(82.4)				(82.4)
Issuance of preferred stock	318.0	325.0		(7.0)
Share repurchases	(3,426.1)			(9.6)			(3,416.5)
Amortization of restricted stock, stock option and performance shares expenses	14.0			34.8			(20.8)
Employee stock purchase plan	2.1			2.1
Distribution of earnings and capital	(0.4)							(0.4)
Ending balance at Sep. 30, 2017	$ 7,451.3	$ 325.0	$ 2.1	$ 8,787.1	$ 2,025.8	$ (73.3)	$ (3,615.4)	$ 0.0