Summary of Information Relating to Stock Option Exercises (Detail) (Stock Option Exercises, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Option Exercises
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Proceeds from stock option exercises	$ 127.4	$ 50.3	$ 36.4
Aggregate intrinsic value	61.3	25.3	19.7
Tax benefit realized upon exercise	$ 23.4	$ 9.6	$ 7.8

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

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+ Details