Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 360.6	$ 347.1
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)
Net Unrealized Gains (Losses) on Debt Securities Available for Sale	199.7	85.6
Net Unrealized Gains (Losses) on Cash Flow Hedges	7.3	(4.3)
Net Foreign Currency Adjustments	25.7	14.8
Net Pension and Other Postretirement Benefit Adjustments	7.0	12.3
Other Comprehensive Income (Loss)	239.7	108.4
Comprehensive Income	$ 600.3	$ 455.5

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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