SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) number in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jan. 01, 2019 USD ($)
Significant Accounting Policies [Line Items]
Number of natural gas distribution services customers	2,200		2,200
Segment Reporting, Disclosure of Major Customers	0	0	0	0
Capital Expenditures Incurred but Not yet Paid			$ 2,400	$ 4,800
Operating Lease, Right-of-Use Asset	$ 37,300		37,300		$ 32,000
Operating Lease, Liability	$ 37,200		$ 37,200		$ 32,000