COMMITMENTS AND CONTINGENCIES Lease and commitments (Details) $ in Thousands, € in Millions		12 Months Ended
		Dec. 31, 2017 USD ($)		Dec. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Future commitments [Line Items]
Operating Leases, Rent Expense		$ 600			$ 600	$ 500
Operating lease renewal option		5 years		5 years
Operating lease obligations, 2018		$ 388
Operating lease obligations, 2019		155
Operating lease obligations, 2020		155
Operating lease obligations, 2021		58
Operating lease obligations, 2022		0
Operating lease obligations, Thereafter		0
Operating lease obligations, Total		756
Total commitments 2018		6,910
Total commitments 2019		155
Total commitments 2020		155
Total commitments 2021		58
Total commitments 2022		0
Total commitments Thereafter		0
Grand Total commitments		7,278
Private Equity Funds [Member]
Future commitments [Line Items]
Private equity and limited partnerships, 2018		6,522	[1]		$ 9,200
Private equity and limited partnerships, 2019		0
Private equity and limited partnerships, 2020		0
Private equity and limited partnerships, 2021		0
Private equity and limited partnerships, 2022		0
Private equity and limited partnerships, Thereafter		0
Private equity and limited partnerships, Total	[1]	6,522
Greenlight Re | Minimum
Future commitments [Line Items]
Annual rent payments		300
Greenlight Re | Maximum
Future commitments [Line Items]
Annual rent payments		$ 500
GRIL
Future commitments [Line Items]
Annual rent payments | €				€ 0.1

[1] Given the nature of these investments, the Company is unable to determine with any degree of accuracy when these commitments will be called. Therefore, for purposes of the above table, the Company has assumed that all commitments with no fixed payment schedules will be called during the year ending December 31, 2018.