EMPLOYEE BENEFITS (Asset Allocation) (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 164,819	$ 157,644	$ 128,430
Actual % of total	100.00%	100.00%
Fixed maturity securities - corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 10,051	$ 11,003
Actual % of total	6.10%	7.00%
Redeemable preferred stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 2,697	$ 3,216
Actual % of total	1.60%	2.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 86,586	$ 87,603
Actual % of total	52.50%	55.60%
Core plus bond separate account fund
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 20,222	$ 17,948
Actual % of total	12.30%	11.40%
U.S. property separate account fund
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 20,841	$ 15,502
Actual % of total	12.60%	9.80%
Arbitrage fund
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 8,716	$ 8,506
Actual % of total	5.30%	5.40%
United Life annuity
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 10,339	$ 9,846
Actual % of total	6.30%	6.20%
Pension Plan Assets, Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 5,367	$ 4,020
Actual % of total	3.30%	2.60%
Minimum | Fixed maturity securities - corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Minimum | Redeemable preferred stock
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation	50.00%
Minimum | Core plus bond separate account fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Minimum | U.S. property separate account fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Minimum | Arbitrage fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Minimum | United Life annuity
Defined Benefit Plan Disclosure [Line Items]
Target allocation	5.00%
Minimum | Pension Plan Assets, Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocation	0.00%
Maximum | Fixed maturity securities - corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Target allocation	15.00%
Maximum | Redeemable preferred stock
Defined Benefit Plan Disclosure [Line Items]
Target allocation	10.00%
Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation	70.00%
Maximum | Core plus bond separate account fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	40.00%
Maximum | U.S. property separate account fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	25.00%
Maximum | Arbitrage fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation	10.00%
Maximum | United Life annuity
Defined Benefit Plan Disclosure [Line Items]
Target allocation	10.00%
Maximum | Pension Plan Assets, Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocation	10.00%