Summary of Significant Accounting Policies - Energy Assets (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
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| Accounting Policies [Abstract] | |||
| Interest costs capitalized | $ 3,817,000 | $ 4,256,000 | $ 1,253,000 |
| Deferred grant income | 6,637,000 | 7,188,000 | |
| Rebates from utility company | $ 0 | $ 0 | $ 0 |
| X | ||||||||||
- Definition Rebates from Utility Company No definition available.
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of interest capitalized during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- 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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