Notes Payable (Details) $ in Thousands  | 
9 Months Ended | ||
|---|---|---|---|
| 
 Oct. 15, 2013  
USD ($) 
 | 
 Sep. 30, 2019  
USD ($) 
 | 
 Oct. 23, 2013  
item 
 | 
|
| Notes Payable | |||
| Periodic payment amount | $ 12,441 | ||
| Sweetwater IDR Bond [Member] | |||
| Notes Payable | |||
| Proceeds from Issuance of Long-term Debt | $ 34,000 | ||
| Due Quarterly Commencing From January 1, 2014 [Member] | Sweetwater IDR Bond [Member] | |||
| Notes Payable | |||
| Fixed interest rate (as a percent) | 5.75% | ||
| Due Quarterly Commencing From January 1, 2015 [Member] | Sweetwater IDR Bond [Member] | |||
| Notes Payable | |||
| Number of installments | item | 28 | 
| X | ||||||||||
- Definition Represents the total number of installment payments to be made on the debt instrument. No definition available. 
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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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 of the required periodic payments applied to principal. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- Definition The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- Details 
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| X | ||||||||||
- Details 
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- Details 
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