Components of Accumulated Other Comprehensive Income (Loss) (AOCI) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Ending Balance	$ (266.4)	$ (236.1)
Net Change	53.3	8.2
Beginning Balance	(319.7)	(244.3)
Net Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Ending Balance	81.7	10.5
Net Change	54.1	4.5
Beginning Balance	27.6	6.0
Net Unrealized Gains (Losses) on Cash Flow Hedges Designations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Ending Balance	(5.8)	4.5
Net Change	(1.1)	1.6
Beginning Balance	(4.7)	2.9
Net Foreign Currency Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Ending Balance	(7.6)	5.8
Net Change	(5.9)	(1.3)
Beginning Balance	(1.7)	7.1
Net Pension and Other Postretirement Benefit Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Ending Balance	(334.7)	(256.9)
Net Change	6.2	3.4
Beginning Balance	$ (340.9)	$ (260.3)

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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