REGULATORY PROCEEDINGS (Details) - USD ($)		3 Months Ended
	Nov. 24, 2015	Mar. 31, 2018	Mar. 31, 2017
Other Proceedings [Abstract]
Effective Date	4.71%
Increase Amount Based On Eligible Plant Improvements Since Last Rate Increase	$ 16,600,000
Delaware [Member]
Rate Proceedings [Abstract]
Percentage of gross water sales		15.00%
Period to complete rate case by law		7 months
Delaware [Member] | Maximum [Member]
Rate Proceedings [Abstract]
Temporary annual rate increase subject to 15% gross water sales limitation		$ 2,500,000
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 held in reserve pending outcome of TCJA impact to customers		$ 748,000
Revenue earned in DSIC rate increases		$ 0	$ 756,000