Debt (Convertible Debenture Terms) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Debt Disclosure [Abstract]
Outstanding principal amount	$ 1,500.0
Unamortized debt discount	534.0
Net debt carrying amount	966.0
Equity Component carrying amount	$ 543.6
Conversion rate (shares of common stock per $1,000 principal)	13.2917
Effective conversion price (per $1,000 of principal)	$ 75.2345

Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

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The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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The price per share of the conversion feature embedded in the debt instrument.

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The ratio applied to the debt for purposes of determining the number of shares of the equity security into which the debt will be converted.

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The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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