NET LOSS PER SHARE (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic net income (loss) per share
Net loss	$ (26,741)	$ (20,917)
Numerator:
Net loss	$ (26,741)	$ (20,917)
Total potentially dilutive common shares (in shares)	26,448	27,836
Convertible Notes
Numerator:
Total potentially dilutive common shares (in shares)	17,931	17,931
Stock options and equivalents
Numerator:
Total potentially dilutive common shares (in shares)	8,517	9,905