RETROCESSION (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Ceded Credit Risk [Line Items]
Loss and loss adjustment expenses incurred, net	$ 168,918,000	$ 81,467,000	$ 379,746,000	$ 283,511,000
Loss and loss expenses recovered and recoverable	16,000,000	200,000	15,900,000	900,000
Loss and loss adjustment expenses recoverable	18,447,000	$ 3,220,000	18,447,000	$ 3,220,000	$ 2,704,000	$ 3,368,000
Funds withheld	16,487,000		16,487,000		5,927,000
Collateral Held in Trust	289,800,000		289,800,000		86,400,000
Provision for uncollectible losses recoverable	0		0		0
Unrated [Member]
Ceded Credit Risk [Line Items]
Loss and loss adjustment expenses recoverable	17,200,000		17,200,000		2,200,000
AM Best, A- Rating [Member]
Ceded Credit Risk [Line Items]
Loss and loss adjustment expenses recoverable	$ 1,200,000		$ 1,200,000		$ 500,000