LIABILITY FOR LOSSES AND SETTLEMENT EXPENSES (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of beginning and ending reserves for losses and settlement expenses [Roll Forward]
Gross reserves at beginning of year	$ 732,612	$ 690,532	$ 678,774
Re-valuation due to foreign currency exchange rates	525	(1,913)	(2,475)
Less ceded reserves at beginning of year	30,923	20,664	23,477
Net reserves at beginning of year	701,164	671,781	657,772
Incurred losses and settlement expenses related to:
Current year	475,843	441,588	427,838
Prior years	(18,684)	(19,619)	(40,941)
Total incurred losses and settlement expenses	457,159	421,969	386,897
Paid losses and settlement expenses related to:
Current year	180,230	179,354	172,652
Prior years	236,905	213,232	200,236
Total paid losses and settlement expenses	417,135	392,586	372,888
Net reserves at end of year	741,188	701,164	671,781
Plus ceded reserves at end of year	36,595	30,923	20,664
Re-valuation due to foreign currency exchange rates	(593)	525	(1,913)
Gross reserves at end of year	$ 777,190	$ 732,612	$ 690,532
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Property and casualty insurance [Member]
Incurred losses and settlement expenses related to:
Prior years	$ (15,300)	$ (15,700)	$ (30,000)
Percentage change in loss and settlement expense reserves for prior accident years (in hundredths)	(3.00%)	(3.20%)	(5.10%)
Paid losses and settlement expenses related to:
Adjustment for favorable (adverse) development included in the reported development amount that had no impact on earnings			$ 5,600
Approximation of the implied amount of favorable development that had an impact on earnings			$ 24,400
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Reinsurance [Member]
Incurred losses and settlement expenses related to:
Prior years	$ (3,400)	$ (3,900)	$ (10,900)
Percentage change in loss and settlement expense reserves for prior accident years (in hundredths)	(1.50%)	(1.90%)	(5.50%)
Affiliated Entity [Member] \| Property and casualty insurance [Member]
Paid losses and settlement expenses related to:
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%

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The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

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Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred and costs incurred in the claim settlement process.

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