COMMITMENTS AND CONTINGENCIES - Part 2 (Details)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies [Line Items]
Number Of Former Manufactured Gas Sites Where We Own Or Retain Legal Responsibility For Environmental Conditions	12
Number of sites with ongoing groundwater monitoring	8
Number Of Sites Soil Remediation Is Completed Or Near Completion	11
Number of sites where regulatory closure has been achieved	3
Environmental Reserve Estimate Range, Low	4
Environmental Reserve Estimate Range, High	7
Environmental Reserve Estimate, Actual	4
Percentage yield of high consequence pipeline areas	30.00%