| Revenue - Capitalized Contract Costs (Details) $ in Thousands | 6 Months Ended | 
|---|---|
| Jun. 30, 2018  USD ($) | |
| Capitalized Contract Cost [Line Items] | |
| Beginning balance | $ 0 | 
| Increases as a result of cumulative catch-up adjustment | 930 | 
| Capitalization during period | 2,448 | 
| Amortization | (59) | 
| Ending balance | 3,319 | 
| Costs to Obtain | |
| Capitalized Contract Cost [Line Items] | |
| Beginning balance | 0 | 
| Increases as a result of cumulative catch-up adjustment | 120 | 
| Capitalization during period | 0 | 
| Amortization | (15) | 
| Ending balance | 105 | 
| Costs to Fulfill | |
| Capitalized Contract Cost [Line Items] | |
| Beginning balance | 0 | 
| Increases as a result of cumulative catch-up adjustment | 810 | 
| Capitalization during period | 2,448 | 
| Amortization | (44) | 
| Ending balance | $ 3,214 | 
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- Definition Capitalized Contract Cost, Cumulative Catch-up Adjustment No definition available. 
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- Definition Capitalized Contract Cost Recorded No definition available. 
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- Definition Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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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 Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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