UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME (LOSS) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Statement [Abstract]
Revenues	$ 295	$ 346	$ 1,548	$ 1,708
Operating expenses
Cost of gas	112	120	701	832
Operation and maintenance	105	114	363	358
Depreciation and amortization	43	40	126	119
Taxes other than income taxes	11	10	36	36
Total operating expenses	271	284	1,226	1,345
Operating income	24	62	322	363
Other income (expense)	1	(1)	4	1
Interest expense, net	(31)	(27)	(92)	(81)
(Loss) earnings before Income Taxes	(6)	34	234	283
Income tax (benefit) expense	(2)	13	85	103
Net (loss) income	(4)	21	149	180
Less net (loss) income attributable to the noncontrolling interest (Note 8)	(1)	(1)	10	10
Net (loss) income attributable to AGL Resources Inc	$ (3)	$ 22	$ 139	$ 170
Per common share data (Note 2)
Basic (loss) earnings per common share attributable to AGL Resources Inc. common shareholders	$ (0.04)	$ 0.29	$ 1.79	$ 2.20
Diluted (loss) earnings per common share attributable to AGL Resources Inc. common shareholders	$ (0.04)	$ 0.29	$ 1.78	$ 2.19
Cash dividends declared per common share	$ 0.45	$ 0.44	$ 1.35	$ 1.32
Weighted-average number of common shares outstanding (Note 2)
Basic	78.1	77.5	77.9	77.3
Diluted	78.1	77.9	78.4	77.7