SEGMENT REPORTING - Geographic information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Gross premiums written	$ 109,787	$ 162,560
Gross premiums by geographical area as a percentage of total gross premiums	100.00%	100.00%
U.S. and Caribbean
Revenue from External Customer [Line Items]
Gross premiums written	$ 86,050	$ 137,651
Gross premiums by geographical area as a percentage of total gross premiums	78.40%	84.70%
Worldwide
Revenue from External Customer [Line Items]
Gross premiums written	$ 22,796	$ 24,909
Gross premiums by geographical area as a percentage of total gross premiums	20.70%	15.30%
Asia
Revenue from External Customer [Line Items]
Gross premiums written	$ 941	$ 0
Gross premiums by geographical area as a percentage of total gross premiums	0.90%	0.00%