REGULATORY PROCEEDINGS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2016
Other Proceedings [Abstract]
Cumulative DSIC Rate	7.41%	3.63%	7.41%	3.63%	5.55%	4.71%
Eligible Plant Improvements - Cumulative Dollars			$ 43,100	$ 24,700	$ 30,400	$ 16,600
Delaware [Member]
Rate Proceedings [Abstract]
Percentage of gross water sales			15.00%
Period to complete rate case by law			7 months
Revenue returned to customers as a result of TCJA			$ 3,800
Delaware [Member] | Maximum [Member]
Rate Proceedings [Abstract]
Temporary annual rate increase subject to 15% gross water sales limitation			$ 2,500
Percentage of rate relief allowed should a rate case not complete			15.00%
Other Proceedings [Abstract]
Distribution System Improvement Charge rate increase applied between base rate filings			7.50%
Distribution System Improvement Charge rate increase within a 12-month period			5.00%
Artesian Water [Member]
Other Proceedings [Abstract]
Revenue earned in DSIC rate increases	$ 900	$ 800	$ 1,800	$ 1,500