STOCK OPTIONS (Details) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended	25 Months Ended
	Jan. 01, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Jun. 30, 2017	Apr. 30, 2015	Mar. 31, 2015
Stock options
Stock-based compensation (in dollars)		$ 1,300,000	$ 1,200,000	$ 2,600,000	$ 2,400,000
Stock Options
Stock options
Granted (in shares)				1,114,463
Expected term				10 years
Options to purchase common stock outstanding (in shares)		4,000,772		4,000,772		3,193,785	4,000,772
Stock option modification (in dollars)		$ 24,000		$ 24,000
Vesting period				48 months
2007 Plan
Stock options
Options to purchase common stock outstanding (in shares)		46,476		46,476		150,207	46,476
2007 Plan | Stock Options
Stock options
Expected term				10 years
2010 Plan
Stock options
Shares available for future grants		322,355		322,355			322,355
Granted (in shares)							0
Options to purchase common stock outstanding (in shares)		1,721,246		1,721,246		1,821,487	1,721,246
2010 Plan | Stock options
Stock options
Expected term				10 years
2015 Plan
Stock options
Shares authorized for issuance		4,322,355		4,322,355			4,322,355	4,000,000
Options to purchase common stock outstanding (in shares)		2,233,050		2,233,050		1,222,085	2,233,050
2015 Plan | Stock options
Stock options
Expected term				10 years
Employee Stock Purchase Plan
Stock options
Shares authorized for issuance									187,500
Percentage of outstanding shares reserved for future issuance				1.00%
Increase in shares of common stock reserved for issuance (in shares)				50,000
Maximum aggregate number of shares reserved for issuance during term of employee stock purchase plan		262,785		262,785		220,771	262,785
Offering Period				6 months
Employee payroll deductions (in dollars)				$ 22,000
Stock-based compensation (in dollars)		$ 8,000	$ 1,000	$ 13,000	$ 2,400
Employee Stock Purchase Plan | Maximum
Stock options
Maximum aggregate number of shares reserved for issuance during term of employee stock purchase plan		1,250,000		1,250,000			1,250,000
Common Stock
Stock options
Stock issued under ESPP (in shares)				7,986		16,729
ASU 2016-09
Stock options
Cumulative effect adjustment (in dollars)	$ 155,000