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	December 31,
	Lives (Years)	2010		2011
		(in millions)
Transmission	39	$	1,632	$	1,720
Distribution	28	5,149		5,327
Other	13	805		780
Total		7,586		7,827
Accumulated depreciation		2,805		2,784
Property, plant and equipment, net		$	4,781	$	5,043

(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	$	259	$	273	$	257
Amortization of securitized regulatory assets	203		289		308
Other amortization	18		20		22
Total depreciation and amortization	$	480	$	582	$	587

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



	December 31,
	2010		2011
Beginning balance	$	22	$	26
Accretion expense	1		1
Revisions in estimates of cash flows	3		(4		)
Ending balance	$	26	$	23

The increase of $3 million in the ARO from the revision of estimate in 2010 is primarily attributable to the decrease in the credit-adjusted risk-free rate used to value the liability as of the end of the periods. The decrease of $4 million in the ARO from the revision of estimate in 2011 is primarily attributable to an increase in the estimated useful lives of the underlying assets. 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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