Short-term Investments (Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	$ 2,097.6	$ 2,014.8
Time deposits	830.3	809.5
Short-term Investments, Total	2,927.9	2,824.3
U.S. Treasury And Agency Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	598.9	527.1
Corporate And Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	394.0	360.5
Certificates of Deposit and Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	719.1	754.0
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	241.9	229.6
Municipal Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	121.1	121.3
Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investment securities	$ 22.6	$ 22.3

Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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