Note 2 - Significant Accounting Policies and Methods of Application (Details) - Potentially Dilutive Common Share Calculation (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Potentially Dilutive Common Share Calculation [Abstract]
Income from continuing operations (2) (in Dollars)	$ 334	[1],[2]	$ 149	[1],[2]
(Loss) income from discontinued operations, net of tax (3) (in Dollars)	(50)	[1],[3]	1	[1],[3]
Net income attributable to AGL Resources Inc. (in Dollars)	$ 284	[1]	$ 150	[1]
Basic weighted average number of shares outstanding (4) (in Shares)	118.5	[1],[4]	117.4	[1],[4]
Effect of dilutive securities (in Shares)	0.4	[1]	0.3	[1]
Diluted weighted average number of shares outstanding (in Shares)	118.9	[1]	117.7	[1]
Basic earnings (loss) per common share
From continuing operations	$ 2.82	[1],[2]	$ 1.27	[1],[2]
From discontinued operations	$ (0.43)	[1],[2]	$ 0.01	[1],[2]
Basic earnings per common share attributable to AGL Resources Inc. common shareholders	$ 2.39	[1]	$ 1.28	[1]
Diluted earnings (loss) per common share
From continuing operations	$ 2.81	[1],[2]	$ 1.26	[1],[2]
From discontinued operations	$ (0.43)	[1],[2]	$ 0.01	[1],[2]
Diluted earnings per common share attributable to AGL Resources Inc. common shareholders	$ 2.38	[1]	$ 1.27	[1]

[1] Amounts revised and or include prior period adjustments. See Note 13 for additional information.

[2] Excludes net income attributable to the noncontrolling interest.

[3] For additional information on our discontinued operations, see Note 12.

[4] Daily weighted average shares outstanding.