STOCKHOLDERS' EQUITY - Common Stock, Warrants and Conversion of 2022 Notes Narrative (Details)	3 Months Ended	27 Months Ended
	Mar. 31, 2020 vote $ / shares shares	Mar. 31, 2020 $ / shares shares	Mar. 05, 2020 $ / shares shares	Dec. 31, 2019 $ / shares shares	May 25, 2018 $ / shares shares	Mar. 06, 2017 $ / shares shares
2022 Notes | Convertible Debt
Class of Stock [Line Items]
Shares issued upon conversion (in shares)	1,100,000	8,400,000
Common Stock Warrant, 2025 Notes
Class of Stock [Line Items]
Warrants to purchase aggregate shares of capital stock (in shares)			8,260,000
Warrants, weighted average exercise price (in USD per share) | $ / shares			$ 161.34
Number of warrants exercised (in shares)	0	0
Common Stock Warrant, 2023 Notes
Class of Stock [Line Items]
Warrants to purchase aggregate shares of capital stock (in shares)					11,100,000
Warrants, weighted average exercise price (in USD per share) | $ / shares					$ 109.26
Number of warrants exercised (in shares)	0	0
Common Stock Warrant, 2022 Notes
Class of Stock [Line Items]
Warrants to purchase aggregate shares of capital stock (in shares)						19,200,000
Warrants, weighted average exercise price (in USD per share) | $ / shares						$ 31.18
Number of warrants exercised (in shares)	0	0
Class A
Class of Stock [Line Items]
Common stock, number of votes entitled for each share held (in votes) | vote	1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000		1,000,000,000
Common stock, par value (in USD per share) | $ / shares	$ 0.0000001	$ 0.0000001		$ 0.0000001
Common stock, shares outstanding (in shares)	359,142,301	359,142,301		352,386,562
Class B
Class of Stock [Line Items]
Common stock, number of votes entitled for each share held (in votes) | vote	10
Common stock, shares authorized (in shares)	500,000,000	500,000,000		500,000,000
Common stock, par value (in USD per share) | $ / shares	$ 0.0000001	$ 0.0000001		$ 0.0000001
Common stock, shares outstanding (in shares)	79,621,335	79,621,335		80,410,158