| Commitments and Contingencies (Details) | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | |
| Revenue | Customer concentration | ||||
| Certain Risks and Concentrations | ||||
| Concentration Risk, Percentage | 72.00% | 61.00% | 67.00% | 58.00% | 
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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. No definition available. 
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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