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Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($) ReportingUnit Customer | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |
Number of reporting units | ReportingUnit | 5 |  |
Foreign currency transaction losses | $ | $ 2 | $ 1 | $ 3
Number of major customers | Customer | 30 |  |
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Percentage of revenue | 10.00% |  |
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Top 30 Customers [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Percentage of revenue | 33.00% |  |

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