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Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Operating Income (Loss) | $ 366.1 | $ 362.1 | $ 134.6

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
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