LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
prior year loss and LAE reserves	$ 31,250,000	$ 2,200	$ 36,157,000
Number of operating segments | segment	1
Private Passenger Automobile Business
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)	$ (39,800,000)	(11,900,000)	(4,300,000)
Professional Liability
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)	(3,600,000)	(3,800,000)	(10,700,000)
Homeowners' Property Contracts
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)	$ 13,500,000	7,500,000	(4,100,000)
General Liability
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)		(2,000,000)
Surety Business
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)		(1,800,000)	(2,200,000)
Hurricane
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)		5,900,000
Reinstatement Premium Previously Recorded
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)		(1,600,000)
Mortgage Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)		$ 4,100,000
Accident & Health
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims and claims adjustment expense, period increase (decrease)			$ (3,700,000)