SEGMENT REPORTING - Geographic information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from External Customer [Line Items]
Gross premiums written	$ 116,689	$ 152,340	$ 226,476	$ 314,900
Gross premiums by geographical area as a percentage of total gross premiums	100.00%	100.00%	100.00%	100.00%
U.S. and Caribbean
Revenue from External Customer [Line Items]
Gross premiums written	$ 94,663	$ 130,637	$ 180,713	$ 268,288
Gross premiums by geographical area as a percentage of total gross premiums	81.10%	85.80%	79.80%	85.10%
Worldwide
Revenue from External Customer [Line Items]
Gross premiums written	$ 20,616	$ 21,231	$ 43,412	$ 46,140
Gross premiums by geographical area as a percentage of total gross premiums	17.70%	13.90%	19.20%	14.70%
Asia
Revenue from External Customer [Line Items]
Gross premiums written	$ 1,410	$ 485	$ 2,351	$ 485
Gross premiums by geographical area as a percentage of total gross premiums	1.20%	0.30%	1.00%	0.20%
Europe
Revenue from External Customer [Line Items]
Gross premiums written	$ 0	$ (13)	$ 0	$ (13)
Gross premiums by geographical area as a percentage of total gross premiums	0.00%	0.00%	0.00%	0.00%