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Fair Value Measurements - Summary of Changes in Fair Value of Level 3 Financial Liabilities (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Beginning balance | $ 31,828 |  |
Reclassification of contingent warrant liability to equity upon exercise of warrants | (3,552) | $ (2,526) | $ (6,171)
Ending balance | 10,464 | 31,828 |
Warrant Liabilities [Member] |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |
Beginning balance | 31,828 | 69,869 |
Initial fair value of warrants issued |  | 10,258 |
Reclassification of contingent warrant liability to equity upon exercise of warrants | (3,552) | (2,526) |
Increase (decrease) in estimated fair value of contingent warrant liabilities upon revaluation | (17,812) | (45,773) |
Ending balance | $ 10,464 | $ 31,828 | $ 69,869

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- Definition Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Noncash value related to the reclassification of a contingent warrant liability to equity upon exercise of warrants during the reporting period + References No definition available. + Details
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