STOCK OPTIONS (Details) - USD ($) $ in Thousands	1 Months Ended		6 Months Ended	12 Months Ended
	Jan. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock options
Options available to purchase/Common Stock outstanding			3,253,310	3,253,310	2,606,737
Exercisable period				6 years	6 years 11 days	6 years 3 months
Expected term of options granted				6 years 7 months 24 days
Vesting period				7 years 9 months 26 days
Stock Options
Stock options
Stock-based compensation expense, net of forfeitures				$ 4,666	$ 2,730	$ 3,136
Expected term of options granted				10 years
Vesting period				48 months
2007 Plan
Stock options
Options available to purchase/Common Stock outstanding			240,863	240,863
Shares available for future grants			0	0
Exercisable period				10 years
2010 Plan
Stock options
Options available to purchase/Common Stock outstanding			2,065,687	2,065,687
Shares available for future grants			322,355	322,355
Shares authorized for issuance			4,000,000	4,000,000
Exercisable period				10 years
2015 Plan
Stock options
Options available to purchase/Common Stock outstanding			946,760	946,760
Shares authorized for issuance			4,322,355	4,322,355
Exercisable period				10 years
Employee Stock Purchase Plan
Stock options
Shares Authorized For Employee Stock Purchase Plan		187,500
Maximum aggregate number of shares reserved for issuance during term of employee stock purchase plan		1,250,000
Offering Period				6 months
Compensation expense related to ESPP				$ 41
Stock repurchased under ESPP				6,948
Employee Stock Purchase Plan | Subsequent event
Stock options
Stock issued under ESPP	6,948
Employee Stock Purchase Plan | Accrued expense
Stock options
Employee payroll deductions			$ 49