Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 2,172.3us-gaap_NetIncomeLoss	$ 64.0us-gaap_NetIncomeLoss	$ 3,405.5us-gaap_NetIncomeLoss	$ 665.1us-gaap_NetIncomeLoss	$ 745.4us-gaap_NetIncomeLoss
Other comprehensive income:
Foreign currency translation adjustments			(136.1)	25.3	23.7
Unrealized holding (loss) / gain on available-for-sale securities (net of taxes of $1.3 million, $0.1 million and $2.5 million)			(5.6)	(2.0)	2.9
Comprehensive income			3,263.8us-gaap_ComprehensiveIncomeNetOfTax	688.4us-gaap_ComprehensiveIncomeNetOfTax	772.0us-gaap_ComprehensiveIncomeNetOfTax
Components of accumulated other comprehensive income
Foreign currency translation adjustments	(25.7)	110.4	(25.7)	110.4
Unrealized holding loss on available-for-sale securities, net of taxes	(5.8)	(0.2)	(5.8)	(0.2)
Accumulated other comprehensive income	$ (31.5)	$ 110.2	$ (31.5)	$ 110.2

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

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Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

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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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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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