EMPLOYEE BENEFIT PLANS (Target Asset Allocation Percentages) (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		100.00%	100.00%
Pension Plan | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		29.00%	27.00%
Pension Plan | Absolute return
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		5.00%	5.00%
Pension Plan | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		8.00%	10.00%
Pension Plan | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		58.00%	58.00%
PBOP Plans
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		100.00%	100.00%
PBOP Plans | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		33.00%	32.00%
PBOP Plans | Absolute return
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		3.00%	3.00%
PBOP Plans | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		6.00%	7.00%
PBOP Plans | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation		58.00%	58.00%
Scenario, Forecast | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	100.00%
Scenario, Forecast | Pension Plan | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	29.00%
Scenario, Forecast | Pension Plan | Absolute return
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	5.00%
Scenario, Forecast | Pension Plan | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	8.00%
Scenario, Forecast | Pension Plan | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	58.00%
Scenario, Forecast | PBOP Plans
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	100.00%
Scenario, Forecast | PBOP Plans | Global equity securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	33.00%
Scenario, Forecast | PBOP Plans | Absolute return
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	3.00%
Scenario, Forecast | PBOP Plans | Real assets
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	6.00%
Scenario, Forecast | PBOP Plans | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total target asset allocation	58.00%