Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 131	$ 69
Short-term investments	58	53
Receivables
Energy marketing receivables	677	607
Gas	362	364
Unbilled revenues	235	216
Other	89	112
Less allowance for uncollectible accounts	28	15
Total receivables, net	1,335	1,284
Inventories
Natural gas stored underground	662	702
Other	46	48
Total inventories	708	750
Regulatory assets	145	131
Prepaid expenses	141	164
Derivative instruments	130	226
Other current assets	20	69
Total current assets	2,668	2,746
Long-term assets and other deferred debits
Property, plant and equipment	10,478	9,779
Less accumulated depreciation	2,131	1,879
Property, plant and equipment, net	8,347	7,900
Goodwill	1,837	1,813
Regulatory assets	944	1,079
Long-term investments	136	128
Intangible assets	96	105
Derivative instruments	14	62
Other	99	80
Total long-term assets and other deferred debits	11,473	11,167
Total assets	14,141	13,913
Current liabilities
Short-term debt	1,377	1,321
Energy marketing trade payable	611	590
Accounts payable - trade	334	294
Current portion of long-term debt and capital leases	226	17
Regulatory liabilities	161	112
Customer credit balances and deposits	143	152
Accrued regulatory infrastructure program costs	121	131
Accrued environmental remediation liabilities	57	37
Accrued taxes	53	49
Accrued interest	53	61
Accrued wages and salaries	34	52
Derivative instruments	33	99
Other current liabilities	135	169
Total current liabilities	3,338	3,084
Long-term liabilities and other deferred credits
Long-term debt	3,327	3,561
Accumulated deferred income taxes	1,588	1,445
Regulatory liabilities	1,477	1,405
Accrued environmental remediation liabilities	387	290
Accrued other retirement benefit costs	268	320
Accrued pension obligations	240	238
Derivative instruments	6	11
Accrued regulatory infrastructure program costs	0	145
Other long-term liabilities and other deferred credits	75	75
Total long-term liabilities and other deferred credits	7,368	7,490
Total liabilities and other deferred credits	10,706	10,574
Common shareholders’ equity
Common stock, $5 par value; 750,000,000 shares authorized; outstanding: 117,855,075 shares at December 31, 2012 and 117,044,803 shares at December 31, 2011	590	586
Additional paid in capital	2,014	1,989
Retained earnings	1,035	967
Accumulated other comprehensive loss	(218)	(217)
Treasury shares, at cost: 216,523 shares at December 31, 2012 and 189,000 shares at December 31, 2011	(8)	(7)
Total common shareholders’ equity	3,413	3,318
Noncontrolling interest	22	21
Total equity	3,435	3,339
Total liabilities and equity	$ 14,141	$ 13,913