SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss Per Share (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 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	21,180	10,206
Employee And Non Employees Stock Option
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	2,856	4,042
Restricted Stock
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	6,280	6,164
1.0% 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	12,044