COMMITMENTS AND CONTINGENCIES Narrative (Details) € in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) facility	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) facility	Sep. 30, 2020 EUR (€)	Sep. 30, 2019 USD ($)	Aug. 26, 2020 USD ($)	Aug. 25, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Number of credit facilities | facility	1		1
Amount of letters of credit issued	$ 133,000,000.0		$ 133,000,000.0					$ 204,500,000
Total equity securities, restricted cash, and cash and cash equivalents fair value pledged as security against the letters of credit	135,600,000		135,600,000					213,400,000
Collateral held in trust	587,500,000		587,500,000					528,700,000
Maximum Facility Limit						$ 275,000,000.0	$ 400,000,000.0
Short term lease cost	$ 400,000	$ 400,000	$ 400,000		$ 400,000
Term of contract	5 years		5 years
Operating lease, ROU asset	$ 100,000		$ 100,000					200,000
Operating lease, liability	100,000		100,000					$ 200,000
Operating lease expense	$ 0	$ 0	$ 0		$ 0
GRIL
Line of Credit Facility [Line Items]
Short term lease cost | €				€ 0.1