DERIVATIVE INSTRUMENTS, BROKER MARGIN DEPOSITS (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Restricted broker margin accounts	$ 6,581	$ 21,929
NJRES [Member]
Restricted broker margin accounts		1,200
Broker Margin, Current Assets [Member] | NJNG [Member]
Restricted broker margin accounts	213	1,713
Broker Margin, Current Assets [Member] | NJRES [Member]
Restricted broker margin accounts	$ 6,368	$ 20,216