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				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Potentially Dilutive Common Share Calculation [Abstract]
Income from continuing operations (2) (in Dollars)	$ 57		$ 44		$ 391		$ 193
Income (loss) from discontinued operations, net of tax (3) (in Dollars)	1		(1)		(49)
Net income attributable to AGL Resources Inc. (in Dollars)	$ 58		$ 43		$ 342		$ 193
Basic weighted average number of shares outstanding (4) (in Shares)	118.8		117.8		118.7		117.6
Effect of dilutive securities (in Shares)	0.4		0.4		0.4		0.3
Diluted weighted average number of shares outstanding (in Shares)	119.2		118.2		119.1		117.9
Basic earnings (loss) per share
From continuing operations	$ 0.48	[1]	$ 0.38	[1]	$ 3.30	[1]	$ 1.65	[1]
From discontinued operations	$ 0.01	[1]	$ (0.01)	[1]	$ (0.42)	[1]		[1]
Basic earnings per common share attributable to AGL Resources Inc. common shareholders	$ 0.49		$ 0.37		$ 2.88		$ 1.65
Diluted earnings (loss) per share
From continuing operations	$ 0.48	[1]	$ 0.38	[1]	$ 3.29	[1]	$ 1.64	[1]
From discontinued operations	$ 0.01	[1]	$ (0.01)	[1]	$ (0.42)	[1]		[1]
Diluted earnings per common share attributable to AGL Resources Inc. common shareholders	$ 0.49		$ 0.37		$ 2.87		$ 1.64

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