Balance Sheet Components (Prepaid Expenses and Other Current Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017
Prepaid Expense and Other Assets [Abstract]
Prepaid expenses	$ 117.1		$ 119.8
Restricted cash	53.9		77.8	$ 135.9
Fair value of financial instruments	7.1		88.9
Equity securities	36.6		79.1
Other current assets	343.2		369.0
Prepaid expenses and other current assets	$ 583.2	$ 784.6	$ 766.1

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Amount of current assets classified as other.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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