NET INCOME (LOSS) PER SHARE - Calculation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income (loss)	$ 39,008	$ (105,891)
Basic shares:
Weighted-average common shares outstanding (in shares)	455,414	435,680
Weighted-average unvested shares (in shares)	(441)	(740)
Weighted-average shares used to compute basic net income (loss) per share (in shares)	454,973	434,940
Diluted shares:
Stock options, restricted stock, and employee stock purchase plan (in shares)	20,972	0
Convertible senior notes (in shares)	322	0
Common stock warrants (in shares)	25,086	0
Weighted-average shares used to compute diluted net loss per share (in shares)	501,353	434,940
Net income (loss) per share:
Basic (in USD per share)	$ 0.09	$ (0.24)
Diluted (in USD per share)	$ 0.08	$ (0.24)