Share-Based Compensation (Details 2) - Share-Based Compensation Expense (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	$ 20.0	$ 12.7
Less: Income tax benefit	(6.5)	(4.4)
Total share-based compensation expense, net of tax	13.5	8.3
Share-Based Compensation Expense, Aggregate Disclosures
Total unrecognized compensation cost related to restricted stock, stock options and the ESPP ($)	163.1
Remaining weighted-average period over which the unrecognized compensation cost related to restricted stock, stock options and the ESPP will be recognized	2 years 4 months 24 days
Cost of revenue
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	4.0	3.8
Research and development
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	3.2	2.8
Sales and marketing
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	2.7	2.1
General and administrative
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	$ 10.1	$ 4.0

Represents the expense 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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.F)

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

-Publisher FASB

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-Publisher SEC

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-Number Topic 14

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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.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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.

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