Property, Plant and Equipment

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

(a) Property, Plant and Equipment

Property, plant and equipment includes the following:



	Weighted Average Useful	December 31,
	Lives (Years)	2011		2012
		(in millions)
Transmission	41	$	1,720	$	1,851
Distribution	29	5,327		5,548
Other	15	780		805
Total		7,827		8,204
Accumulated depreciation		2,784		2,839
Property, plant and equipment, net		$	5,043	$	5,365

(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	$	273	$	257	$	265
Amortization of securitized regulatory assets	289		308		442
Other amortization	20		22		22
Total depreciation and amortization	$	582	$	587	$	729

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



	December 31,
	2011			2012
Beginning balance	$	26		$	23
Accretion expense	1			1
Revisions in estimates of cash flows	(4		)	5
Ending balance	$	23		$	29

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. The increase of $5 million in the ARO from the revision of estimate in 2012 is primarily attributable to a decrease in the estimated useful lives of certain assets. There were no material additions or settlements during the years ended December 31, 2011 and 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.

+ References+ Details