DERIVATIVE INSTRUMENTS - VOLUME (Details) MWh in Thousands, $ in Millions		Mar. 31, 2016 USD ($) Bcf MWh	Sep. 30, 2015 USD ($) Bcf	Jun. 01, 2015 USD ($)
Derivative [Line Items]
Notional amount | $				$ 125
NJNG [Member] | Treasury Lock [Member]
Derivative [Line Items]
Notional amount | $		$ 125	$ 125
NJNG [Member] | Long [Member] | Futures [Member]
Derivative [Line Items]
Volume	[1]	15.2	25.8
NJNG [Member] | Long [Member] | Physical [Member]
Derivative [Line Items]
Volume		5.9	0.0
NJRES [Member] | SREC [Member]
Derivative [Line Items]
Volume | MWh	[2]	48
NJRES [Member] | Long [Member] | Physical [Member]
Derivative [Line Items]
Volume	[2]	137.4	48.2
NJRES [Member] | Long [Member] | Options [Member]
Derivative [Line Items]
Volume		3.6	1.2
NJRES [Member] | Short [Member] | Futures [Member]
Derivative [Line Items]
Volume		88.6	91.1

[1] Not included is the notional amount of $125 million related to NJNG’s treasury lock agreement.

[2] Not included are 48,000 SRECs that are open as of March 31, 2016.