COMMITMENTS AND CONTINGENCIES Narrative (Details) € in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) facility	Dec. 31, 2019 EUR (€)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Letter of credit facility | facility	1
Aggregate amount of letters of credit issued	$ 204,500,000			$ 208,300,000
Total equity securities, restricted cash, and cash and cash equivalents fair value pledged as security against the letters of credit	213,400,000			221,700,000
Collateral held in trust	528,700,000			$ 463,400,000
Short-term lease, cost	$ 500,000
Lessee, operating lease, term of contract	5 years
Operating lease, right-of-use asset	$ 300,000
Lease liability	300,000
Credit facility maximum lending capacity	6,000,000
Unused commitments to extend credit	400,000
GRIL
Line of Credit Facility [Line Items]
Short-term lease, cost | €		€ 0.1
Accounting Standards Update 2016-02
Line of Credit Facility [Line Items]
Operating lease, right-of-use asset			$ 300,000
Lease liability			$ 300,000
Advisory fee
Line of Credit Facility [Line Items]
Other commitment	$ 2,000,000