NET INCOME (LOSS) PER COMMON SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net Income (Loss), basic	$ 784,803	$ 55,036	$ 837,001	$ (38,872)
Add: Interest on convertible notes	7,070	937	18,333	0
Net Income (Loss), diluted	$ 791,873	$ 55,973	$ 855,334	$ (38,872)
Denominator:
Weighted average number of shares outstanding, basic	181,142	179,289	180,592	178,873
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted-average common shares outstanding, diluted	197,674	185,924	194,959	178,873
Net Income (Loss) per common share, basic (in dollars per share)	$ 4.33	$ 0.31	$ 4.63	$ (0.22)
Net Income (Loss) per common share, diluted (in dollars per share)	$ 4.01	$ 0.30	$ 4.39	$ (0.22)
Options to purchase common stock
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	1,731	1,560	1,728	0
Common stock issuable under the 2020 notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	3,983	0	3,983	0
Common stock issuable under the 2024 notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	3,970	3,970	3,970	0
Common stock issuable under the 2027 Notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	4,365	0	2,373	0
Unvested restricted stock units
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	1,926	669	1,765	0
Common stock potentially issuable for ESPP purchases
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	346	231	337	0
Common stock held by the NQDC
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	211	205	211	0