Note 13 - Revision to Prior Period Financial Statements (Details) - Revisions to Condensed Consolidated Statements of Income (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Operating revenues	$ 889,000,000	[1]	$ 805,000,000	[1]	$ 3,351,000,000	[1]	$ 2,417,000,000	[1]
Operating expenses
Cost of goods sold	402,000,000	[1]	353,000,000	[1]	1,802,000,000	[1]	1,273,000,000	[1]
Operation and maintenance	211,000,000	[1]	204,000,000	[1]	500,000,000	[1]	435,000,000	[1]
Depreciation and amortization	95,000,000	[1]	103,000,000	[1]	188,000,000	[1]	205,000,000	[1]
Taxes other than income taxes	42,000,000	[1]	43,000,000	[1]	130,000,000	[1]	112,000,000	[1]
Total operating expenses	750,000,000	[1]	703,000,000	[1]	2,620,000,000	[1]	2,025,000,000	[1]
Gain on disposition of assets			11,000,000	[1]			11,000,000	[1]
Operating income	139,000,000	[1]	113,000,000	[1]	731,000,000	[1]	403,000,000	[1]
Other income	2,000,000	[1]	6,000,000	[1]	5,000,000	[1]	11,000,000	[1]
Interest expense, net	(45,000,000)		(44,000,000)		(91,000,000)		(89,000,000)
Income before income taxes	96,000,000		75,000,000		645,000,000		325,000,000
Income tax expense	37,000,000		30,000,000		240,000,000		121,000,000
Income from continuing operations	59,000,000		45,000,000		405,000,000		204,000,000
Loss from discontinued operations	1,000,000		(1,000,000)		(49,000,000)
Net income	60,000,000		44,000,000		356,000,000		204,000,000
Less net income attributable to the noncontrolling interest	2,000,000		1,000,000		14,000,000		11,000,000
Net income attributable to AGL Resources Inc.	58,000,000		43,000,000		342,000,000		193,000,000
Basic earnings per common share (2)
Continuing operations (in Dollars per share)	$ 0.48	[2]	$ 0.38	[2]	$ 3.30	[2]	$ 1.65	[2]
Discontinued operations (in Dollars per share)	$ 0.01	[2]	$ (0.01)	[2]	$ (0.42)	[2]		[2]
Basic earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ 0.49		$ 0.37		$ 2.88		$ 1.65
Diluted earnings (loss) per common share (2)
Continuing operations (in Dollars per share)	$ 0.48	[2]	$ 0.38	[2]	$ 3.29	[2]	$ 1.64	[2]
Discontinued operations (in Dollars per share)	$ 0.01	[2]	$ (0.01)	[2]	$ (0.42)	[2]		[2]
Diluted earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ 0.49		$ 0.37		$ 2.87		$ 1.64
Scenario, Previously Reported [Member]
Operating revenues	902,000,000	[3]	816,000,000	[4]	3,376,000,000	[3]	2,438,000,000	[4]
Operating expenses
Cost of goods sold	402,000,000	[3]	353,000,000	[4]	1,802,000,000	[3]	1,273,000,000	[4]
Operation and maintenance	211,000,000	[3]	205,000,000	[4]	500,000,000	[3]	437,000,000	[4]
Depreciation and amortization	95,000,000	[3]	103,000,000	[4]	188,000,000	[3]	206,000,000	[4]
Taxes other than income taxes	42,000,000	[3]	43,000,000	[4]	130,000,000	[3]	112,000,000	[4]
Total operating expenses	750,000,000	[3]	704,000,000	[4]	2,620,000,000	[3]	2,028,000,000	[4]
Gain on disposition of assets			11,000,000	[4]			11,000,000	[4]
Operating income	152,000,000	[3]	123,000,000	[4]	756,000,000	[3]	421,000,000	[4]
Other income	2,000,000	[3]	7,000,000	[4]	5,000,000	[3]	12,000,000	[4]
Interest expense, net	(48,000,000)	[3]	(46,000,000)	[4]	(96,000,000)	[3]	(92,000,000)	[4]
Income before income taxes	106,000,000	[3]	84,000,000	[4]	665,000,000	[3]	341,000,000	[4]
Income tax expense	41,000,000	[3]	33,000,000	[4]	248,000,000	[3]	127,000,000	[4]
Income from continuing operations	65,000,000	[3]	51,000,000	[4]	417,000,000	[3]	214,000,000	[4]
Loss from discontinued operations	1,000,000	[3]	(1,000,000)	[4]	(49,000,000)	[3]		[4]
Net income	66,000,000	[3]	50,000,000	[4]	368,000,000	[3]	214,000,000	[4]
Less net income attributable to the noncontrolling interest	2,000,000	[3]	1,000,000	[4]	14,000,000	[3]	11,000,000	[4]
Net income attributable to AGL Resources Inc.	64,000,000	[3]	49,000,000	[4]	354,000,000	[3]	203,000,000	[4]
Basic earnings per common share (2)
Continuing operations (in Dollars per share)	$ 0.53	[2],[3]	$ 0.42	[2],[4]	$ 3.40	[2],[3]	$ 1.72	[2],[4]
Discontinued operations (in Dollars per share)	$ 0.01	[2],[3]	$ (0.01)	[2],[4]	$ (0.42)	[2],[3]		[2],[4]
Basic earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ 0.54	[3]	$ 0.41	[4]	$ 2.98	[3]	$ 1.72	[4]
Diluted earnings (loss) per common share (2)
Continuing operations (in Dollars per share)	$ 0.53	[2],[3]	$ 0.42	[2],[4]	$ 3.39	[2],[3]	$ 1.72	[2],[4]
Discontinued operations (in Dollars per share)	$ 0.01	[2],[3]	$ (0.01)	[2],[4]	$ (0.42)	[2],[3]		[2],[4]
Diluted earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ 0.54	[3]	$ 0.41	[4]	$ 2.97	[3]	$ 1.72	[4]
Restatement Adjustment [Member]
Operating revenues	(13,000,000)		(11,000,000)		(25,000,000)		(21,000,000)
Operating expenses
Operation and maintenance			(1,000,000)				(2,000,000)
Depreciation and amortization							(1,000,000)
Total operating expenses			(1,000,000)				(3,000,000)
Operating income	(13,000,000)		(10,000,000)		(25,000,000)		(18,000,000)
Other income			(1,000,000)				(1,000,000)
Interest expense, net	3,000,000		2,000,000		5,000,000		3,000,000
Income before income taxes	(10,000,000)		(9,000,000)		(20,000,000)		(16,000,000)
Income tax expense	(4,000,000)		(3,000,000)		(8,000,000)		(6,000,000)
Income from continuing operations	(6,000,000)		(6,000,000)		(12,000,000)		(10,000,000)
Net income	(6,000,000)		(6,000,000)		(12,000,000)		(10,000,000)
Net income attributable to AGL Resources Inc.	$ (6,000,000)		$ (6,000,000)		$ (12,000,000)		$ (10,000,000)
Basic earnings per common share (2)
Continuing operations (in Dollars per share)	$ (0.05)	[2]	$ (0.04)	[2]	$ (0.10)	[2]	$ (0.07)	[2]
Discontinued operations (in Dollars per share)		[2]		[2]		[2]		[2]
Basic earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ (0.05)		$ (0.04)		$ (0.10)		$ (0.07)
Diluted earnings (loss) per common share (2)
Continuing operations (in Dollars per share)	$ (0.05)	[2]	$ (0.04)	[2]	$ (0.10)	[2]	$ (0.08)	[2]
Discontinued operations (in Dollars per share)		[2]		[2]		[2]		[2]
Diluted earnings per common share attributable to AGL Resources Inc. common shareholders (in Dollars per share)	$ (0.05)		$ (0.04)		$ (0.10)		$ (0.08)

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

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

[3] Reflects the reclassification of the Tropical Shipping amounts as discontinued operations, as filed in the Original Filing.

[4] Reflects the reclassification of the Tropical Shipping amounts as discontinued operations, as filed in our Original Filing.