SUBSEQUENT EVENTS - Narrative (Details) - USD ($) shares in Millions, $ in Millions	Aug. 09, 2019	Sep. 09, 2014
Convertible debt
Subsequent Event [Line Items]
Interest rate		2.50%
Convertible debt | Subsequent Event
Subsequent Event [Line Items]
Debt exchange, face amount to be exchanged	$ 200.0
Senior Notes | Subsequent Event
Subsequent Event [Line Items]
Debt instrument, authorized amount for use to make certain investments or payments	30.0
Debt instrument, exit fee due, if circumstances met	4.4
New Convertible Notes, Due August 15, 2024 | Convertible debt | Subsequent Event
Subsequent Event [Line Items]
Debt exchange, face amount to be issued	$ 120.0
Interest rate	5.00%
Debt exchange, cash to be paid	$ 30.0
New Convertible Notes, Due August 15, 2024 | Senior Notes | Subsequent Event
Subsequent Event [Line Items]
Debt exchange, common shares to be issued (in shares)	15.8