Note 2 - Significant Accounting Policies and Methods of Application (Tables)

12 Months Ended

Dec. 31, 2012

In millions	2012		2011		2010
Retail operations	$	3	$	5	$	0
Wholesale services		19		31		8
Midstream operations		1		0		0

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

Dollars in millions	Total (1)		# of top counterparties		Concentration risk %
Credit exposure	$	211		20		50	%

Property, Plant and Equipment [Table Text Block]

In millions	2012		2011
Transportation and distribution	$	7,992	$	7,579
Storage caverns		1,149		931
Shipping vessels and containers		145		146
Other		820		747
Construction work in progress		372		376
Total gross PP&E		10,478		9,779
Less accumulated depreciation		2,131		1,879
Total net PP&E	$	8,347	$	7,900

Schedule of Expected Amortization Expense [Table Text Block]

In millions	Amortization Expense
2013	$	9
2014		9
2015		9
2016		9
2017		8

Schedule of Other Nonoperating Income (Expense) [Table Text Block]

In millions	2012		2011		2010
Equity investment income	$	13	$	1	$	0
AFUDC - equity		6		4		2
Other, net		5		2		(3	)
Total other income (expense)	$	24	$	7	$	(1	)

Schedule of Weighted Average Number of Shares [Table Text Block]

In millions (except per share amounts)	2012		2011		2010
Net income attributable to AGL Resources Inc.	$	271	$	172	$	234
Denominator:
Basic weighted average number of shares outstanding (1)		117.0		80.4		77.4
Effect of dilutive securities		0.5		0.5		0.4
Diluted weighted average number of shares outstanding		117.5		80.9		77.8
Basic and diluted earnings per share
Basic	$	2.32	$	2.14	$	3.02
Diluted	$	2.31	$	2.12	$	3.00

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	December 31,
In millions	2012		2011		2010
Twelve months ended		0.0		0.0		0.8

Schedule of Regulatory Assets and Liabilities [Text Block]

In millions	2012		2011
Regulatory assets
Recoverable regulatory infrastructure program costs	$	47	$	48
Recoverable ERC		38		7
Recoverable pension and other retirement benefit costs		19		29
Other regulatory assets		41		47
Total regulatory assets - current		145		131
Recoverable ERC		438		351
Recoverable pension and other retirement benefit costs		196		262
Recoverable regulatory infrastructure program costs		167		305
Long-term debt fair value adjustment		90		99
Other regulatory assets		53		62
Total regulatory assets - long-term		944		1,079
Total regulatory assets	$	1,089	$	1,210
Regulatory liabilities
Accrued natural gas costs	$	93	$	53
Bad debt rider		37		30
Accumulated removal costs		16		14
Other regulatory liabilities		15		15
Total regulatory liabilities - current		161		112
Accumulated removal costs		1,393		1,321
Unamortized investment tax credit		29		32
Regulatory income tax liability		27		27
Bad debt rider		17		14
Other regulatory liabilities		11		11
Total regulatory liabilities - long-term		1,477		1,405
Total regulatory liabilities	$	1,638	$	1,517

Depreciation [Member]

Property, Plant and Equipment [Table Text Block]

	2012			2011			2010
Atlanta Gas Light (1)		2.6	%		2.6	%		2.5	%
Chattanooga Gas (1)		2.5	%		2.5	%		2.8	%
Elizabethtown Gas (2)		2.4	%		2.5	%		2.4	%
Elkton Gas (2)		2.4	%		2.4	%		2.3	%
Florida City Gas (2)		3.9	%		3.9	%		3.7	%
Nicor Gas (2)		4.1	%		4.1	%		n/a
Virginia Natural Gas (1)		2.5	%		2.5	%		3.0	%

Estimated Useful Lives [Member]

Property, Plant and Equipment [Table Text Block]

In years	Estimated useful life
Transportation equipment	5	-	10
Shipping vessels	20	-	25
Storage caverns	40	-	60
Other		up to 40

Authorized AFUDC Rates [Member]

Property, Plant and Equipment [Table Text Block]

	2012			2011			2010
Atlanta Gas Light		8.10	%		8.10	%		8.10	%
Chattanooga Gas		7.41	%		7.41	%		7.41	%
Elizabethtown Gas (1)		0.51	%		0.53	%		0.40	%
AFUDC (in millions) (2)	$	9		$	6		$	3