FAIR VALUE - Long-Term Debt and Convertible Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Carrying Amount | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Construction loan	$ 24,263	$ 24,866
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Construction loan	24,263	24,866
2028 Convertible notes | Carrying Amount | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	786,711	0
2028 Convertible notes | Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	1,101,413	0
2027 Convertible notes | Carrying Amount | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	498,707	483,909
2027 Convertible notes | Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	774,328	843,741
2025 Convertible notes | Carrying Amount | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	248,965	319,696
2025 Convertible notes | Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible notes	$ 419,015	$ 592,482