Property, Plant and Equipment

12 Months Ended

Dec. 31, 2012

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)	2011		2012
		(in millions)
Natural Gas Distribution	32	$	3,959	$	4,321
Competitive Natural Gas Sales and Services	26	76		80
Interstate Pipelines	56	2,675		2,803
Field Services	42	1,754		2,359
Other property	12	55		52
Total		8,519		9,615
Accumulated depreciation and amortization:
Natural Gas Distribution		1,069		1,194
Competitive Natural Gas Sales and Services		20		25
Interstate Pipelines		302		355
Field Services		72		118
Other property		26		22
Total accumulated depreciation and amortization		1,489		1,714
Property, plant and equipment, net		$	7,030	$	7,901

(b) Depreciation and Amortization

The following table presents depreciation and amortization expense for 2010, 2011 and 2012:



	Year Ended December 31,
	2010		2011		2012
	(in millions)
Depreciation expense	$	232	$	244	$	267
Amortization expense	16		18		18
Total depreciation and amortization expense	$	248	$	262	$	285

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



	December 31,
	2011		2012
Beginning balance	$	58	$	132
Accretion expense	3		6
Revisions in estimates of cash flows	71		(3		)
Ending balance	$	132	$	135

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. The decrease of $3 million in the ARO from the revision of estimate in 2012 is primarily attributable to a steel pipe replacement effort during 2012 which shifted the cost of removal obligation further into the future and lowered the current liability. There were no material additions or settlements during the years ended December 31, 2011 or 2012.

- 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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