UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Millions	Common Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Premium on Common Stock [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Total
AGL Resources Inc. Common Shareholders Equity, Beginning Balance at Dec. 31, 2009	$ 390	$ (116)	$ 679	$ 848	$ (21)	$ 39	$ 1,819
Common stock shares, Beginning Balance (in shares) at Dec. 31, 2009	77.5
Profit Loss				170		10	180
Other comprehensive loss		(16)					(16)
Dividends paid on common shares				(102)	3		(99)
Purchase of additional 15% ownership interest in SouthStar		(1)	(51)			(6)	(58)
Distributions to noncontrolling interest (Note 8)						(27)	(27)
Purchase of treasury shares, amount					(5)		(5)
Purchase of treasury shares, shares (in shares)	(0.1)
Issuance of treasury shares, amount			(8)	(3)	22		11
Issuance of treasury shares, shares(in shares)	0.6
Stock-based compensation expense (net of tax)			8		1		9
AGL Resources Inc. Common Shareholders Equity, Ending Balance at Sep. 30, 2010	390	(133)	628	913	0	16	1,814
Common stock shares, Ending Balance (in shares) at Sep. 30, 2010	78.0
AGL Resources Inc. Common Shareholders Equity, Beginning Balance at Dec. 31, 2010	391	(150)	631	943	(2)	23	1,836
Common stock shares, Beginning Balance (in shares) at Dec. 31, 2010	78.0
Profit Loss				139		10	149
Other comprehensive loss		(1)					(1)
Dividends paid on common shares			3	(105)			(102)
Benefit Dividend Reinvestment And Stock Purchase Plans, Shares (in shares)	0.7
Distributions to noncontrolling interest (Note 8)						(16)	(16)
Benefit Dividend Reinvestment And Stock Purchase Plans, Value	3		10		(2)		11
Purchase of treasury shares, amount					(2)		(2)
Stock-based compensation expense (net of tax)			6				6
AGL Resources Inc. Common Shareholders Equity, Ending Balance at Sep. 30, 2011	$ 394	$ (151)	$ 650	$ 977	$ (6)	$ 17	$ 1,881
Common stock shares, Ending Balance (in shares) at Sep. 30, 2011	78.7