Summary of Significant Accounting Policies - Energy Assets (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2019 |
Dec. 31, 2018 |
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| Accounting Policies [Abstract] | ||
| Interest costs capitalized | $ 788 | $ 994 |
| Minimum qualifying operating period for prorated repayments of grants | 5 years | |
| Property, Plant and Equipment [Line Items] | ||
| Deferred grant income | $ 6,499 | $ 6,637 |
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- Definition Government Grant, Qualification Requirement, Prorated Repayment Effective Period from Date Placed in Service No definition available.
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- References No definition available.
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- Definition Amount of interest capitalized during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of unearned revenue or income classified as other, expected to be taken into income after one year or the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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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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