Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	PREFERRED STOCK	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	TREASURY STOCK
Beginning balance at Dec. 31, 2018	$ 10,508.3	$ 882.0	$ 408.6	$ 1,068.5	$ 10,776.8	$ (453.7)	$ (2,173.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	347.1				347.1
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)	108.4					108.4
Dividends Declared:
Common Stock	(133.7)				(133.7)
Preferred Stock	(17.3)				(17.3)
Stock Options and Awards	126.0						126.0
Stock Purchased	(257.4)						(257.4)
Treasury Stock Transactions — Stock Options and Awards	(120.5)			(120.5)
Stock Options and Awards — Amortization	55.3			55.3
Ending balance at Mar. 31, 2019	10,616.2	882.0	408.6	1,003.3	10,972.9	(345.3)	(2,305.3)
Beginning balance at Dec. 31, 2019	11,091.0	1,273.4	408.6	1,013.1	11,656.7	(194.7)	(3,066.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	360.6				360.6
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)	239.7					239.7
Dividends Declared:
Common Stock	(148.6)				(148.6)
Preferred Stock	(19.0)				(19.0)
Redemption of Preferred Stock, Series C	(400.0)	(388.5)			(11.5)
Stock Options and Awards	137.7						137.7
Stock Purchased	(296.8)						(296.8)
Treasury Stock Transactions — Stock Options and Awards	(129.0)			(129.0)
Stock Options and Awards — Amortization	54.2			54.2
Ending balance at Mar. 31, 2020	$ 10,879.7	$ 884.9	$ 408.6	$ 938.3	$ 11,828.1	$ 45.0	$ (3,225.2)