CONSOLIDATED STATEMENTS OF COMMON STOCK EQUITY - USD ($) $ in Thousands		Total		Common Stock	Premium on Common Stock		Accumulated Other Comprehensive (Loss) Income	Treasury Stock And Other		Retained Earnings
Beginning Balance (in shares) at Sep. 30, 2014				84,356,000
Beginning Balance at Sep. 30, 2014		$ 966,166		$ 218,223	$ 199,739		$ (5,594)	$ (121,031)		$ 674,829
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		180,960								180,960
Other comprehensive loss		(3,800)					(3,800)
Common stock issued:
Incentive compensation plan (in shares)				359,000
Incentive compensation plan		5,908		$ 895	5,013
Divident reinvestment plan (in shares)	[1]			1,149,000
Dividend reinvestment plan		27,538	[1]	$ 1,720	6,722	[1]		19,096	[1]
Tax benefits from stock plans		(1,344)			(1,344)
Cash dividend declared ($1.0375 per share in 2017, $.975 per share in 2016, and $.915 per share in 2015)		(78,044)								(78,044)
Treasury stock and other (in shares)				(333,000)
Treasury stock and other		9,572			(199)			9,771
Ending Balance (in shares) at Sep. 30, 2015				85,531,000
Ending Balance at Sep. 30, 2015		$ 1,106,956		$ 220,838	209,931		(9,394)	(92,164)		777,745
Common stock issued:
Dividend Reinvestment Plan waiver discount feature (in shares)		688,000
Net income		$ 131,672								131,672
Other comprehensive loss		(5,761)					(5,761)
Incentive compensation plan (in shares)				325,000
Incentive compensation plan		9,399		$ 816	8,583
Divident reinvestment plan (in shares)	[1]			471,000
Dividend reinvestment plan	[1]	16,063			(2,879)			18,942
Cash dividend declared ($1.0375 per share in 2017, $.975 per share in 2016, and $.915 per share in 2015)		(83,861)								(83,861)
Treasury stock and other (in shares)				(241,000)
Treasury stock and other		$ (7,877)			(55)			(7,822)
Ending Balance (in shares) at Sep. 30, 2016		86,086,355		86,086,000
Ending Balance at Sep. 30, 2016		$ 1,166,591		$ 221,654	215,580		(15,155)	(81,044)		825,556
Common stock issued:
Dividend Reinvestment Plan waiver discount feature (in shares)		0
Net income		$ 132,065								132,065
Other comprehensive loss		11,899					11,899
Incentive compensation plan (in shares)				241,000
Incentive compensation plan		5,694		$ 604	5,090
Divident reinvestment plan (in shares)	[1]			472,000
Dividend reinvestment plan	[1]	17,622			(946)			18,568
Cash dividend declared ($1.0375 per share in 2017, $.975 per share in 2016, and $.915 per share in 2015)		(89,637)								(89,637)
Treasury stock and other (in shares)				(243,000)
Treasury stock and other		$ (7,591)			(28)			(7,563)
Ending Balance (in shares) at Sep. 30, 2017		86,555,507		86,556,000
Ending Balance at Sep. 30, 2017		$ 1,236,643		$ 222,258	$ 219,696		$ (3,256)	$ (70,039)		$ 867,984
Common stock issued:
Dividend Reinvestment Plan waiver discount feature (in shares)		0

[1] The DRP allows NJR, at its option, to use newly issued shares to raise capital. During fiscal 2015, NJR issued approximately 688,000 new shares through the waiver discount feature of its DRP. There were no new shares issued through the waiver discount feature during fiscal 2016 and fiscal 2017.