Summary of Significant Accounting Policies - Impairment of Long-Lived Assets (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Accounting Policies [Abstract] | |||
| Impairment charges | $ 0 | $ 0 | $ 0 |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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