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Derivative Instruments - Summary of the Effect of Derivatives Designated as Cash Flow Hedging Instruments (Details) - Foreign exchange contract - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Revenues |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Net Gains/(Losses) Reclassified from AOCI into Operating Income (in millions) | $ 18.3 | $ 118.6 | $ (42.5)
Operating expenses |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Net Gains/(Losses) Reclassified from AOCI into Operating Income (in millions) | 3.3 | (3.3) | 0.2
Cash flows, revenue | Revenues |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative instruments, net, pretax | (9.9) | 2.9 | 10.8
Cash flows, operating expenses | Operating expenses |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (loss) on derivative instruments, net, pretax | $ 0.0 | $ 0.2 | $ (0.1)

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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
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- Definition Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e689-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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