CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Comprehensive income attributable to AGL Resources Inc. (net of tax)
Net (loss) income attributable to AGL Resources Inc	$ 172	$ 234	$ 222
Other Comprehensive Income Reclassification Of Defined Benefit Plans Net Gain Loss Recognized In Net Periodic Benefit Cost Net Of Tax	(65)	(28)	17
Derivative financial instruments unrealized losses arising during the period	(5)	(14)	(12)
Reclassification of derivative financial instruments realized losses included in net income	3	9	13
Other comprehensive loss	(67)	(33)	18
Comprehensive (loss) income	105	201	240
Comprehensive income attributable to noncontrolling interest (net of tax)
Less net (loss) income attributable to the noncontrolling interest (Note 8)	14	16	27
Derivative financial instruments unrealized losses arising during the period	(1)	(1)	(7)
Reclassification of derivative financial instruments realized losses included in net income	1	2	7
Other comprehensive income	0	1	0
Comprehensive (loss) income	14	17	27
Total comprehensive income (net of tax) including portion attributable to noncontrolling interest (net of tax)
Net (loss) income	186	250	249
Other Comprehensive Income Reclassification Of Defined Benefit Plans Net Gain Loss Recognized In Net Periodic Benefit Cost Net Of Tax	(65)	(28)	17
Derivative financial instruments unrealized losses arising during the period	(6)	(15)	(19)
Reclassification of derivative financial instruments realized losses included in net income	4	11	20
Other comprehensive loss	(67)	(32)	18
Comprehensive (loss) income	$ 119	$ 218	$ 267