v3.8.0.1

Summary of Significant Accounting Policies - New Accounting Pronouncements, Adopted (Details) $ in Millions | Dec. 31, 2017 USD ($)
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Accounting Standards Update 2014-09 | Retained Earnings |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |
Cumulative effect of New Accounting Principle in period of adoption | $ 17

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