Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant, and Equipment [Table Text Block]

The following table presents nonregulated and regulated Property, plant, and equipment – net as presented on the Consolidated Balance Sheet for the years ended:

	Estimated Useful Life  (1) (Years)	Depreciation Rates (1) (%)	December 31,
			2018			2017
			(Millions)
Nonregulated:
Natural gas gathering and processing facilities	5 - 40		$	15,324		$	18,440
Construction in progress	Not applicable		778			566
Other	2 - 45		2,356			2,776
Regulated:
Natural gas transmission facilities		1.20 - 6.97	17,312			14,460
Construction in progress	Not applicable	Not applicable	965			1,637
Other	5 - 45	1.35 - 33.33	1,926			1,634
Total property, plant, and equipment, at cost			38,661			39,513
Accumulated depreciation and amortization			(11,157		)	(11,302		)
Property, plant, and equipment — net			$	27,504		$	28,211

__________

(1) Estimated useful life and depreciation rates are presented as of December 31, 2018. Depreciation rates and estimated useful lives for regulated assets are prescribed by the FERC.

Asset Retirement Obligation [Table Text Block]

The following table presents the significant changes to our ARO, of which $968 million and $946 million are included in Regulatory liabilities, deferred income, and other with the remaining current portion in Accrued liabilities at December 31, 2018 and 2017, respectively.

	December 31,
	2018			2017
	(Millions)
Beginning balance	$	998		$	862
Liabilities incurred	21			33
Liabilities settled	(19		)	(16		)
Accretion expense (1)	71			141
Revisions (2)	(39		)	(22		)
Ending balance	$	1,032		$	998

___________

(1) The decrease in accretion expense in 2018 primarily reflects the absence of a 2017 adjustment associated with obligations identified from certain Transco land agreements.

(2) Several factors are considered in the annual review process, including inflation rates, current estimates for removal cost, market risk premiums, discount rates, and the estimated remaining useful life of the assets. The 2018 revisions reflect changes in removal cost estimates, decreases in the estimated remaining useful life of certain assets and increases in the discount rates used in the annual review process. The 2017 revisions reflect changes in removal cost estimates and decreases in the estimated remaining useful life of certain assets and discount rates used in the annual review process.