| Long-term Supply Contract (Details) - USD ($) $ in Thousands | 12 Months Ended | |||
|---|---|---|---|---|
| Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 01, 2014 | |
| Commitments and Contingencies Disclosure [Abstract] | ||||
| Supply agreement liability | $ 27,300 | |||
| Gain on contract termination | $ 0 | $ 0 | $ 20,612 | |
| X | ||||||||||
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- Definition Long-term Supply Commitment, Amount No definition available. 
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| X | ||||||||||
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- References No definition available. 
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| X | ||||||||||
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- Definition Gain (loss) related to the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one party, or a failure to perform. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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