COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016	Mar. 31, 2018
Commitments and Contingencies [Line Items]
Number Of Former Manufactured Gas Sites Where We Own Or Retain Legal Responsibility For Environmental Conditions			12
AAO associated with MGP costs requested amount, cap	$ 15.0
Regulatory asset expected to be recorded for MGP costs accrued at January 1, 2017	$ 5.9
Number of sites where we have completed or addressed removal of the source of soil contamination according to plans approved by KDHE.			11
Number of sites with ongoing groundwater monitoring			8
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%