COMMITMENTS AND CONTINGENCIES - Sublease Income (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Operating Leased Assets [Line Items]
2017 (remaining three months)	$ 75
2018	127
Total future minimum sublease payments	202
New York
Operating Leased Assets [Line Items]
2017 (remaining three months)	42
2018	127
Total future minimum sublease payments	169
Menlo Park
Operating Leased Assets [Line Items]
2017 (remaining three months)	33
2018	0
Total future minimum sublease payments	$ 33