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Segment and Geographic Information - Additional Information (Details) | 12 Months Ended
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Dec. 31, 2017 Customer_Focused_Area Segment | Dec. 31, 2016 | Dec. 31, 2015
Operating Segments [Abstract] |  |  |
Number of customer focused areas | Customer_Focused_Area | 2 |  |
Number of segments | Segment | 1 |  |
Revenue | Customer concentration risk | Top two customers |  |  |
Disclosure of major customers [line items] |  |  |
Concentration risk percentage | 31.00% | 30.00% |
Revenue | Customer concentration risk | Cisco Systems |  |  |
Disclosure of major customers [line items] |  |  |
Concentration risk percentage | 18.00% | 19.00% |
Revenue | Customer concentration risk | Juniper Networks |  |  |
Disclosure of major customers [line items] |  |  |
Concentration risk percentage | 13.00% | 11.00% |
Revenue | Customer concentration risk | Top three customers |  |  |
Disclosure of major customers [line items] |  |  |
Concentration risk percentage |  |  | 38.00%

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- Definition Concentration Risk, Percentage + References No definition available. + Details
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- Definition Number Of Customer Focused Areas + References No definition available. + Details
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Period Type: | duration

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- Definition Number of Reportable Segments + References No definition available. + Details
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Balance Type: | na
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- Definition Operating Segments [Abstract] + References No definition available. + Details
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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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Namespace Prefix: |
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- Details
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- Details
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- Details
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Period Type: |