Fair Value Measurement - Summary of Fair Values of Assets and Liabilities Measured at Fair Value On Recurring and NonRecurring Basis (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Cash, cash equivalents, and restricted cash | $ 777 | $ 3,640 | $ 9,276 | $ 3,970 |
| Warrants potentially settleable in cash | 569 | 1,476 | ||
| Quoted Prices in Active Markets Level 1 [Member] | ||||
| Cash, cash equivalents, and restricted cash | 777 | 3,640 | ||
| Warrants potentially settleable in cash | ||||
| Significant Other Observable Inputs Level 2 [Member] | ||||
| Cash, cash equivalents, and restricted cash | ||||
| Warrants potentially settleable in cash | ||||
| Unobservable Inputs Level 3 [Member] | ||||
| Cash, cash equivalents, and restricted cash | ||||
| Warrants potentially settleable in cash | $ 569 | $ 1,476 |
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- Definition Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Fair value portion of warrants not settleable in cash classified as equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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