Property, Plant and Equipment

12 Months Ended

Dec. 31, 2011

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment Disclosure [Text Block]

Property, Plant and Equipment

(a) Property, Plant and Equipment

Property, plant and equipment includes the following:



	Weighted Average Useful Lives	December 31,
	(Years)	2010		2011
		(in millions)
Natural Gas Distribution	32	$	3,642	$	3,959
Competitive Natural Gas Sales and Services	27	71		76
Interstate Pipelines	57	2,594		2,675
Field Services	46	1,583		1,754
Other property	13	49		55
Total		7,939		8,519
Accumulated depreciation and amortization:
Natural Gas Distribution		954		1,069
Competitive Natural Gas Sales and Services		16		20
Interstate Pipelines		265		302
Field Services		43		72
Other property		25		26
Total accumulated depreciation and amortization		1,303		1,489
Property, plant and equipment, net		$	6,636	$	7,030

(b) Depreciation and Amortization

The following table presents depreciation and amortization expense for 2009, 2010 and 2011:



	Year Ended December 31,
	2009		2010		2011
	(in millions)
Depreciation expense	$	211	$	232	$	244
Amortization expense	18		16		18
Total depreciation and amortization expense	$	229	$	248	$	262

A reconciliation of the changes in the asset retirement obligation (ARO) liability is as follows (in millions):



	December 31,
	2010			2011
Beginning balance	$	60		$	58
Accretion expense	4			3
Revisions in estimates of cash flows	(6		)	71
Ending balance	$	58		$	132

The decrease of $6 million in the ARO from the revision of estimate in 2010 is primarily attributable to changes in the estimated lives of some of the assets underlying the liability. The increase of $71 million in the ARO from the revision of estimate in 2011 is primarily attributable to an increase in the disposal costs used in the cash flow assumptions. There were no material additions or settlements during the years ended December 31, 2010 and 2011.

- Definition

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

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