REVENUE Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Accounts Receivable	$ 243,395	$ 202,379
Unbilled Revenues	62,601	73,377
South Jersey Gas Company
Disaggregation of Revenue [Line Items]
Accounts Receivable	128,583	78,571
Unbilled Revenues	44,287	$ 54,980
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Accounts Receivable	(41,016)
Unbilled Revenues	10,776
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | South Jersey Gas Company
Disaggregation of Revenue [Line Items]
Accounts Receivable	(50,012)
Unbilled Revenues	$ 10,693