Condensed Consolidated Statements of Other Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Net income	$ 296		$ 160
Retirement benefit plans
Reclassification of actuarial losses to net benefit cost (net of income tax of $1 for the three months ended March 31, 2014, and $2 for the three months ended March 31, 2013)	1		4
Reclassification of prior service credits to net benefit cost			(1)
Retirement benefit plans	1		3
Cash flow hedges, net of tax
Net derivative instrument gains arising during the period (net of income tax of $1 for the three months ended March 31, 2013)	4	[1]	2	[1]
Reclassification of realized derivative (gains) losses to net income (net of income tax of $1 for the three months ended March 31, 2013)	(4)	[1]	2	[1]
Cash flow hedges, net			4
Other comprehensive income, net of tax	1		7
Comprehensive income	297		167
Less comprehensive income attributable to noncontrolling interest	12		10
Comprehensive income attributable to AGL Resources Inc.	$ 285		$ 157

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