Revenues - Schedule of Contract Liabilities (Details) - USD ($) $ in Thousands |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2019 |
Dec. 31, 2018 |
|
| Contract with Customer, Liability [Roll Forward] | ||
| Balance, beginning of period | $ 4,304 | $ 15,000 |
| Deduction for recognition of revenue | (2,054) | (15,000) |
| Increase for deferral of shortfall payments | 153 | 4,246 |
| Increase for deferral of customer prepayments | 243 | 58 |
| Deduction of shortfall payments due to contract renegotiations | (1,350) | |
| Balance, end of period | $ 1,296 | $ 4,304 |
| X | ||||||||||
- Definition Contract With Customer, Liability, Deduction Of Shortfall Payments Due To Contract Renegotiations No definition available.
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| X | ||||||||||
- Definition Contract with Customer, Liability, Period Increase From Deferred Customer Payments No definition available.
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| X | ||||||||||
- Definition Contract with Customer, Liability, Period Increase From Deferred Shortfall Payments No definition available.
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| X | ||||||||||
- Definition Contract with Customer, Liability No definition available.
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| X | ||||||||||
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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