STOCK OPTIONS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock option
Options available to purchase/Common Stock outstanding	10,445,662	8,055,522
Exercisable period	6 years 11 days	6 years 3 months	6 years 3 months
Vesting period	5 years 1 month 28 days
Stock Options
Stock option
Stock-based compensation expense, net of forfeitures	2,730	3,136	1,233
Expected term of options granted	10 years
Vesting period	48 months
2007 Plan
Stock option
Options available to purchase/Common Stock outstanding	1,692,309
Shares available for future grants	0
Exercisable period	10 years
2010 Plan
Stock option
Options available to purchase/Common Stock outstanding	8,753,353
Shares available for future grants	1,748,500
Shares authorized for issuance	11,000,000
Exercisable period	10 years