Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 267.9	$ 263.0	$ 544.0	$ 508.4
Other Comprehensive Income (Loss) (Net of Tax and Reclassifications)
Net Unrealized Gains on Securities Available for Sale	1.6	33.5	20.9	108.2
Net Unrealized Gains (Losses) on Cash Flow Hedges	2.3	0.5	(3.0)	6.6
Foreign Currency Translation Adjustments	4.9	6.3	6.9	10.2
Pension and Other Postretirement Benefit Adjustments	4.3	4.0	6.3	8.1
Other Comprehensive Income (Loss)	13.1	44.3	31.1	133.1
Comprehensive Income	$ 281.0	$ 307.3	$ 575.1	$ 641.5

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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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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