ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NET INCOME (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Net income (loss)	$ (8,468)	$ 27,185	$ (9,356)	$ (9,315)	$ (8,947)	$ (9,549)	$ (8,734)	$ (8,440)	$ 46	$ (35,670)	$ (38,379)
Weighted-average shares:
Basic (in shares)									158,036,162	153,540,341	128,380,800
Effect of dilutive securities from stock options and restricted stock awards (in shares)									4,627,732
Diluted (in shares)									162,663,894	153,540,341	128,380,800
Net income (loss) per share:
Basic (in dollars per share)									$ 0.00	$ (0.23)	$ (0.30)
Diluted (in dollars per share)									$ 0.00	$ (0.23)	$ (0.30)