Condensed Consolidated Statements of Financial Position (Unaudited) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011
Current assets
Cash and cash equivalents	$ 91		$ 69		$ 165
Short-term investments	60		53		0
Receivables
Energy marketing receivables	397		607		512
Gas, unbilled and other receivables	305		692		144
Less allowance for uncollectible accounts	31		15		17
Total receivables	671		1,284		639
Inventories	778		750		635
Regulatory assets	158	[1]	131	[2]	99
Derivative instruments	144		226		132
Other current assets	233		233		131
Total current assets	2,135		2,746		1,801
Long-term assets and other deferred debits
Property, plant and equipment	10,281		9,779		6,521
Less accumulated depreciation	2,069		1,879		1,886
Property, plant and equipment, net	8,212		7,900		4,635
Goodwill	1,817		1,813		418
Regulatory assets	1,086	[1]	1,079	[2]	532
Derivative instruments	15		62		36
Other long-term assets and other deferred debits	330		313		37
Total long-term assets and other deferred debits	11,460		11,167		5,658
Total assets	13,595	[3]	13,913	[4]	7,459	[3]
Current liabilities
Short-term debt	1,048		1,321		0
Energy marketing trade payables	444		590		586
Accounts payable - trade	292		294		124
Current portion of long-term debt and capital leases	226		17		17
Customer deposits and credit balances	159		152		39
Accrued regulatory infrastructure program costs	122		131		119
Accrued expenses	119		162		87
Regulatory liabilities	117	[1]	112	[2]	34
Accrued environmental remediation liabilities	61		37		23
Derivative instruments	37		99		45
Other current liabilities	139		169		66
Total current liabilities	2,764		3,084		1,140
Long-term liabilities and other deferred credits
Long-term debt	3,330		3,561		2,687
Accumulated deferred income taxes	1,555		1,445		895
Regulatory liabilities	1,465	[1]	1,405	[2]	296
Accrued environmental remediation liabilities	365		290		166
Accrued other retirement benefit costs	296		320		29
Accrued pension obligations	213		238		151
Accrued regulatory infrastructure program costs	123		145		138
Derivative instruments	5		11		14
Other long-term liabilities and other deferred credits	81		75		62
Total long-term liabilities and other deferred credits	7,433		7,490		4,438
Total liabilities and other deferred credits	10,197		10,574		5,578
Equity
Common stock, $5 par value; 750,000,000 shares authorized; outstanding: 117,743,809 shares at September 30, 2012, 117,044,803 shares at December 31, 2011 and 78,539,528 shares at September 30, 2011	590		586		394
Additional paid in capital	2,012		1,989		650
Retained earnings	990		967		977
Accumulated other comprehensive loss	(203)		(217)		(151)
Treasury shares	(8)		(7)		(6)
Total common shareholders’ equity	3,381		3,318		1,864
Noncontrolling interest	17		21		17
Total equity	3,398		3,339		1,881
Total liabilities and equity	$ 13,595		$ 13,913		$ 7,459

[1] The increase in regulatory assets and liabilities from December 31, 2011, includes an increase in recoverable ERC due to revised estimates of our ERC liabilities made during the second quarter of 2012 of $103 million, which primarily related to Nicor Gas' former manufactured gas plant sites in Illinois. See Note 9 - Commitments, Guarantees and Contingencies for additional ERC disclosures.

[2] The increase in regulatory assets and liabilities from September 30, 2011, includes $545 million related to the addition of Nicor Gas' regulatory assets and includes $1,330 million related to the addition of Nicor Gas' regulatory liabilities.

[3] Identifiable assets are those used in each segment's operations.

[4] Identifiable assets are those assets used in each segment's operations.