SEGMENT REPORTING Schedule of Revenue by Major Customers (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Revenue, Major Customer [Line Items]
Number of operating segments | segment									1
Concentration risk, percentage									100.00%	100.00%	100.00%
Gross premiums written	$ 98,470	$ 110,607	$ 152,340	$ 162,560	$ 135,143	$ 115,154	$ 142,109	$ 175,125	$ 523,977	$ 567,531	$ 692,651
Broker Concentration Risk | Gross Premiums Written
Revenue, Major Customer [Line Items]
Concentration risk, percentage									80.80%	86.80%	78.90%
Gross premiums written									$ 423,544	$ 492,696	$ 546,509
Broker Concentration Risk | Gross Premiums Written | Guy Carpenter (Marsh)
Revenue, Major Customer [Line Items]
Concentration risk, percentage									56.70%	66.40%	52.90%
Gross premiums written									$ 297,150	$ 376,696	$ 366,390
Broker Concentration Risk | Gross Premiums Written | Trean Re
Revenue, Major Customer [Line Items]
Concentration risk, percentage									16.30%	8.00%	7.90%
Gross premiums written									$ 85,323	$ 45,446	$ 54,799
Broker Concentration Risk | Gross Premiums Written | Aon Benfield
Revenue, Major Customer [Line Items]
Concentration risk, percentage									7.80%	12.40%	18.10%
Gross premiums written									$ 41,071	$ 70,554	$ 125,320
Broker Concentration Risk | Gross Premiums Written | All others
Revenue, Major Customer [Line Items]
Concentration risk, percentage									19.20%	13.20%	21.10%
Gross premiums written									$ 100,433	$ 74,835	$ 146,142