Property, Plant and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Text Block]

Property, Plant and Equipment

(a) Property, Plant and Equipment

Property, plant and equipment includes the following:

	Weighted Average Useful	December 31,
	Lives (in years)	2016		2015
		(in millions)
Transmission	44	$	2,402	$	2,196
Distribution	31	6,965		6,556
Other	14	1,473		1,390
Total		10,840		10,142
Accumulated depreciation		3,443		3,209
Property, plant and equipment, net		$	7,397	$	6,933

(b) Depreciation and Amortization

The following table presents depreciation and amortization expense for 2016, 2015 and 2014:

	Year Ended December 31,
	2016		2015		2014
	(in millions)
Depreciation expense	$	349	$	316	$	295
Amortization of securitized regulatory assets	455		365		441
Other amortization	34		24		32
Total depreciation and amortization	$	838	$	705	$	768

(c) AROs

A reconciliation of the changes in the ARO liability is as follows:

	December 31,
	2016			2015
	(in millions)
Beginning balance	$	37		$	36
Accretion expense	1			1
Revisions in estimates of cash flows	(5		)	—
Ending balance	$	33		$	37

Houston Electric recorded AROs associated with the removal of asbestos and asbestos-containing material in its buildings, including substation building structures. Houston Electric also recorded AROs relating to treated wood poles for electric distribution, distribution transformers containing PCB (also known as Polychlorinated Biphenyl), and underground fuel storage tanks. The estimates of future liabilities were developed using historical information, and where available, quoted prices from outside contractors.

The decrease of $5 million in the ARO from the revision in estimates in 2016 is primarily attributable to the reduction in disposal costs. There were no material additions or settlements during the years ended December 31, 2016 and 2015.