OTHER BALANCE SHEET AMOUNTS - Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Accrued compensation	$ 42,877	$ 33,626
Accrued commissions	11,603	18,834
Accrued interest	18,923	8,625
Other accrued expenses	20,862	16,990
Total accrued expenses	$ 94,265	$ 78,075