Acquisitions and Discontinued Operations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Significant Acquisitions and Disposals [Line Items]
Gain (loss) on foreign exchange	$ (1.0)	$ (1.9)	$ 3.0
Gain on discontinued operations, after taxes			10.8
Contribution to charitable foundation that offset gain from disposal of discontinued operation	$ 1.7

Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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The aggregate foreign currency transaction gain (loss) (both realized and unrealized) included in determining net income for the reporting period. Excludes foreign currency transactions designated as hedges of net investment in a foreign entity and intercompany foreign currency transactions that are of a long-term nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements. For certain enterprises, primarily banks, that are dealers in foreign exchange, foreign currency transaction gains (losses) may be disclosed as dealer gains (losses).

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