Condensed Consolidated Statements of Other Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Net income	$ 28		$ 9	$ 242		$ 183
Retirement benefit plans
Reclassification of actuarial losses to net benefit cost (net of income tax of $3 and $8 for the three and nine months ended September 30, 2013, and $2 and $6 for the three and nine months ended September 30, 2012)	3		2	11		10
Reclassification of prior service credits to net benefit cost (net of income tax of $(1) for the nine months ended September 30, 2013)	(2)			(3)
Retirement benefit plans	1	[1]	2	8	[1]	10
Cash flow hedges, net of tax
Reclassification of realized derivative instrument (gains) losses to net income (net of income tax of $1 for the nine months ended September 30, 2013 and $1 and $2 for the three and nine months ended September 30, 2012)		[1]	2	2	[1]	4
Cash flow hedges, net		[1]	2	2	[1]	4
Other comprehensive income, net of tax	1	[1]	4	10	[1]	14
Comprehensive income	29		13	252		197
Less comprehensive income attributable to noncontrolling interest				11		10
Comprehensive income attributable to AGL Resources Inc.	$ 29		$ 13	$ 241		$ 187

[1] All amounts are net of income taxes. Amounts in parentheses indicate debits to accumulated other comprehensive loss.