EMPLOYEE BENEFITS - Schedule of Assumptions used To Calculate Pension and SERP and PBOP (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)		4.20%
Expected Long-Term Rate of Return (in percentage)		8.25%
Compensation/Progression Rate (in percentage)		3.50%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)		4.22%
Expected Long-Term Rate of Return (in percentage)		8.25%
Minimum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)	3.27%		4.85%
Expected Long-Term Rate of Return (in percentage)	8.25%		8.25%
Compensation/Progression Rate (in percentage)	3.50%		3.50%
Minimum [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)	2.88%		4.78%
Expected Long-Term Rate of Return (in percentage)	8.25%		8.25%
Maximum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)	4.89%		5.03%
Expected Long-Term Rate of Return (in percentage)	8.25%		8.25%
Compensation/Progression Rate (in percentage)	3.50%		4.00%
Maximum [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in percentage)	4.09%		5.10%
Expected Long-Term Rate of Return (in percentage)	8.25%		8.25%