LOSS PER SHARE - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net loss	$ (27,345)	$ (29,620)	$ (124,100)	$ (77,598)
Basic shares:
Weighted-average common shares outstanding (in shares)	337,635	154,464	336,406	152,827
Weighted-average unvested shares (in shares)	(3,147)	(5,211)	(3,500)	(5,539)
Weighted-average shares used to compute basic net loss per share (in shares)	334,488	149,253	332,906	147,288
Diluted shares:
Weighted-average shares used to compute diluted loss per share (in shares)	334,488	149,253	332,906	147,288
Net loss per share:
Basic (in USD per share)	$ (0.08)	$ (0.20)	$ (0.37)	$ (0.53)
Diluted (in USD per share)	$ (0.08)	$ (0.20)	$ (0.37)	$ (0.53)