Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands					12 Months Ended
	Dec. 01, 2016	Jan. 07, 2015	Mar. 10, 2014	Sep. 09, 2013	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Minimum lease payments					$ 1,211
Future minimum sublease payments					470
Rent expense					782	$ 667
Rental income					349	$ 132
New York, New York
Loss Contingencies [Line Items]
Future minimum sublease payments					292
Menlo Park, California
Loss Contingencies [Line Items]
Future minimum sublease payments					178
Tel Aviv, Israel
Loss Contingencies [Line Items]
Initial annual rent	$ 12
Office space | New York, New York
Loss Contingencies [Line Items]
Term of lease (in years)				5 years
Initial annual rent				$ 139
Monthly rent installment				$ 12
Minimum lease payments					266
Security deposit					$ 69
Percentage of annual rent increase					2.50%
Future minimum sublease payments					$ 292
Office space | Menlo Park, California
Loss Contingencies [Line Items]
Initial annual rent			$ 165
Minimum lease payments					157
Percentage of annual rent increase			3.00%
Future minimum sublease payments					178
Office space | East Palo Alto, California
Loss Contingencies [Line Items]
Initial annual rent		$ 425
Minimum lease payments					$ 790
Security deposit		$ 231
Percentage of annual rent increase		3.00%