BENEFIT PLANS (Fair Values of Pension Plan Assets) (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	$ 456,238	$ 435,692
Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	115,795	120,802
Investments In The Fair Value Hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	572,033	556,494
Interest In Common/Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	367,105	387,785
Private Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	5,152	4,728
Total [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	944,290	949,007
Fair Value, Inputs, Level 1 [Member] | Debt Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	16	549
Fair Value, Inputs, Level 1 [Member] | Investments In The Fair Value Hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	16	549
Fair Value, Inputs, Level 2 [Member] | Debt Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	456,238	435,692
Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	115,779	120,253
Fair Value, Inputs, Level 2 [Member] | Investments In The Fair Value Hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	572,017	555,945
Fair Value, Inputs, Level 3 [Member] | Debt Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Fair Value, Inputs, Level 3 [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	0	0
Fair Value, Inputs, Level 3 [Member] | Investments In The Fair Value Hierarchy [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension plan assets	$ 0	$ 0