RELATED PARTY TRANSACTIONS (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2014 USD ($) Bcf / d	Sep. 30, 2015 USD ($) contract Bcf	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)
Related Party Transaction [Line Items]
Approximate annual demand fees under agreement from April 1 2010 to March 31 2020		$ 9,300
Number of asset management agreements | contract		3
NJRES to Steckman Ridge and Iroquios Affiliates [Member]
Related Party Transaction [Line Items]
Demand fees recognized pertaining to related party agreement		$ 6,600	$ 6,200	$ 6,100
NJRES to Steckman Ridge Affiliate [Member]
Related Party Transaction [Line Items]
Due to related parties	$ 187	375	187
NJRES to Iroquois Affiliate [Member]
Related Party Transaction [Line Items]
Due to related parties	389	$ 403	389
NJNG to NJRES Affilate [Member]
Related Party Transaction [Line Items]
Asset management agreement, period		10 years
Natural gas sold at cost under asset management agreement (in Bcf) | Bcf		3
NJNG to Steckman RIdge and Iroquios Afffiliates [Member]
Related Party Transaction [Line Items]
Demand fees recognized pertaining to related party agreement		$ 6,300	6,400	$ 5,900
NJNG to Steckman RIdge Affiliate [Member]
Related Party Transaction [Line Items]
Due to related parties	775	775	775
NJNG to Iroquois Affiliate [Member]
Related Party Transaction [Line Items]
Due to related parties	$ 48	$ 48	$ 48
NJNG to PennEast Affiliate [Member]
Related Party Transaction [Line Items]
Transportation precedent agreement, period	15 years
Transportation capacity under precedent agreement from NJNG with PennEast (MMcf) | Bcf / d	0.18