Equity, Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	$ (13.8)
Other comprehensive loss before reclassifications	(18.3)
Amount reclassified from accumulated other comprehensive income	2.9
Other comprehensive loss, net of tax	(15.4)	(62.7)
Balance as of March 31, 2015	(29.2)
Cost of revenues	410.1us-gaap_CostOfRevenue	450.0us-gaap_CostOfRevenue
Sales and marketing	220.2us-gaap_SellingAndMarketingExpense	273.4us-gaap_SellingAndMarketingExpense
General and administrative	55.2us-gaap_GeneralAndAdministrativeExpense	74.9us-gaap_GeneralAndAdministrativeExpense
Research and development	248.7us-gaap_ResearchAndDevelopmentExpense	264.0us-gaap_ResearchAndDevelopmentExpense
Unrealized Gains (Losses) on Available-for- Sale Securities
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	8.4
Other comprehensive loss before reclassifications	(0.8)
Amount reclassified from accumulated other comprehensive income	(0.2)
Other comprehensive loss, net of tax	(1.0)
Balance as of March 31, 2015	7.4
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	(4.2)
Other comprehensive loss before reclassifications	(6.4)
Amount reclassified from accumulated other comprehensive income	3.1
Other comprehensive loss, net of tax	(3.3)
Balance as of March 31, 2015	(7.5)
Cost of revenues	0.9
Sales and marketing	2.1
General and administrative	0.2
Research and development	(0.1)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	(18.0)
Other comprehensive loss before reclassifications	(11.1)
Amount reclassified from accumulated other comprehensive income	0
Other comprehensive loss, net of tax	(11.1)
Balance as of March 31, 2015	$ (29.1)

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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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The aggregate cost of goods produced and sold and services rendered during the reporting period.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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