Share-Based Compensation - Share-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total expense, pre-tax	$ 49.4us-gaap_ShareBasedCompensation	$ 48.5us-gaap_ShareBasedCompensation	$ 55.0us-gaap_ShareBasedCompensation
Tax benefit related to awards	(15.5)	(15.6)	(16.6)
Total expense, net of tax	33.9	32.9	38.4
Stock Options [Member]
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total expense, pre-tax	24.2	24.7	32.4
RSUs [Member]
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total expense, pre-tax	$ 25.2	$ 23.8	$ 22.6

The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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