Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 500	$ 313	$ 275
Retirement benefit plans, net of tax
Actuarial (loss) gain arising during the period (net of income tax of $48, $46 and $16)	(71)	66	(17)
Prior service cost arising during the period (net of income tax of $1)			1
Reclassification of actuarial loss to net benefit cost (net of income tax of $6, $10 and $9)	9	15	13
Reclassification of prior service cost to net benefit cost (net of income tax of $1, $2 and $2)	(1)	(3)	(2)
Retirement benefit plans, net	(63)	78	(5)
Cash flow hedges, net of tax
Net derivative instrument (loss) gain arising during the period (net of income tax of $2, $1 and $-)	(6)	1	(2)
Reclassification of realized derivative (gain) loss to net income (net of income tax of $2, $1 and $3	(3)	3	6
Cash flow hedges, net	(9)	4	4
Other comprehensive income (loss), net of tax	(72)	82	(1)
Comprehensive income	428	395	274
Less comprehensive income attributable to noncontrolling interest	16	18	15
Comprehensive income attributable to AGL Resources Inc.	$ 412	$ 377	$ 259