Income Taxes - Valuation Allowance (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Income Taxes | ||
| Increase in valuation allowance | $ 8.0 | $ 18.5 |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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