FAIR VALUE, DEBT (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Capital leases		$ 46,900	$ 49,900
Fair Value, Inputs, Level 2 [Member] | NJNG [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	[1]	582,845	432,845
Fair Value, Inputs, Level 2 [Member] | NJNG [Member] | Fair Market Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		584,240	453,773
Fair Value, Inputs, Level 2 [Member] | NJR [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		225,000	125,000
Fair Value, Inputs, Level 2 [Member] | NJR [Member] | Fair Market Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		$ 233,079	$ 133,136

[1] Excludes capital leases of $46.9 million and $49.9 million as of September 30, 2015 and 2014, respectively.