LINES OF CREDIT (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Line of Credit Facility [Line Items]
Total Facility	$ 210,000,000
Usage	129,600,000
Available Liquidity	80,400,000
Average borrowings outstanding during the period	108,500,000	40,800,000
Maximum amounts outstanding during the period	136,900,000	66,000,000
Weighted average borrowing cost	0.50%	0.25%
Minimum
Line of Credit Facility [Line Items]
Financial covenant, ratio of indebtedness to consolidated total capitalization minimum	0.65
Revolving Credit Facility
Line of Credit Facility [Line Items]
Total Facility	200,000,000
Usage	129,600,000
Available Liquidity	70,400,000
Expiration Date	May 2018
Uncommitted Bank Lines
Line of Credit Facility [Line Items]
Total Facility	10,000,000
Usage	0
Available Liquidity	10,000,000
Expiration Date	Various
South Jersey Gas Commercial Paper Program
Line of Credit Facility [Line Items]
Total Facility	$ 200,000,000
Fixed maturities of notes, at maximum number of days (in days)	270 days