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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss Per Share (Details) - shares shares in Thousands | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Common shares not included in the computation of diluted net loss per share |  |
Potentially issuable common shares not included in the computation of diluted net loss per share because they would have an anti-dilutive effect | 18,747 | 9,166
Stock Options |  |
Common shares not included in the computation of diluted net loss per share |  |
Potentially issuable common shares not included in the computation of diluted net loss per share because they would have an anti-dilutive effect | 3,284 | 3,613
Restricted Stock Awards |  |
Common shares not included in the computation of diluted net loss per share |  |
Potentially issuable common shares not included in the computation of diluted net loss per share because they would have an anti-dilutive effect | 6,315 | 5,553
Convertible Notes |  |
Common shares not included in the computation of diluted net loss per share |  |
Potentially issuable common shares not included in the computation of diluted net loss per share because they would have an anti-dilutive effect | 9,148 |

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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