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Summary of Significant Accounting Policies Discussion Adoption of ASU 2016-02 (Details) - USD ($) $ in Millions |  | 12 Months Ended
--- | --- | ---
Jan. 01, 2019 | Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification |  | $ (22.5)
Accounting Standards Update 2016-02 [Member] | Operating Lease Right-of-Use Assets [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | $ 109.3 |
Accounting Standards Update 2016-02 [Member] | Assets [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 109.3 |
Accounting Standards Update 2016-02 [Member] | Operating Lease Liabilities, Current [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 41.8 |
Accounting Standards Update 2016-02 [Member] | Other Current Liabilities [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 41.8 |
Accounting Standards Update 2016-02 [Member] | Operating Lease Liabilities, Noncurrent [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 67.5 |
Accounting Standards Update 2016-02 [Member] | Liabilities, Total [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | $ 109.3 |

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