Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 234.6	$ 204.5	$ 734.5	$ 567.8
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)
Net Unrealized Gains (Losses) on Securities Available for Sale	(7.0)	(5.7)	24.7	32.3
Net Unrealized Gains (Losses) on Cash Flow Hedges	3.2	(7.4)	5.3	(6.4)
Foreign Currency Translation Adjustments	(2.3)	(3.6)	(2.4)	(10.5)
Pension and Other Postretirement Benefit Adjustments	6.1	3.5	18.4	10.5
Other Comprehensive Income (Loss)	0.0	(13.2)	46.0	25.9
Comprehensive Income	234.6	191.3	780.5	593.7
Note: Changes in Other-Than-Temporary-Impairment (OTTI) Losses	0.0	0.0	0.0	(4.6)
Investment Security Gains (Losses), net	0.0	0.0	0.0	0.7
Noncredit-related OTTI Losses Recorded in/(Reclassified from) OCI	0.0	0.3	(0.3)	0.6
Investment Security Gains (Losses), net	$ 0.0	$ 0.3	$ (0.3)	$ (3.3)