Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

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,
			2017			2016
			(Millions)
Nonregulated:
Natural gas gathering and processing facilities (2)	5 - 40		$	18,440		$	19,523
Construction in progress	Not applicable		566			412
Other (2)	2 - 45		2,776			3,092
Regulated:
Natural gas transmission facilities		1.20 - 6.97	14,460			12,692
Construction in progress	Not applicable	Not applicable	1,637			1,603
Other	5 - 45	1.35 - 33.33	1,634			1,590
Total property, plant, and equipment, at cost			39,513			38,912
Accumulated depreciation and amortization			(11,302		)	(10,484		)
Property, plant, and equipment — net			$	28,211		$	28,428

__________

(1) Estimated useful life and depreciation rates are presented as of December 31, 2017. Depreciation rates and estimated useful lives for regulated assets are prescribed by the FERC.

(2) The 2016 presentation has been changed to reflect $890 million of right-of-way assets previously presented in Natural gas gathering and processing facilities, now in Other.

Asset Retirement Obligation [Table Text Block]

The following table presents the significant changes to our ARO, of which $946 million and $801 million are included in Regulatory liabilities, deferred income, and other with the remaining current portion in Accrued liabilities at December 31, 2017 and 2016, respectively.

	December 31,
	2017			2016
	(Millions)
Beginning balance	$	862		$	915
Liabilities incurred	33			24
Liabilities settled	(16		)	(8		)
Accretion expense (1)	141			69
Revisions (2)	(22		)	(138		)
Ending balance	$	998		$	862

___________

(1) The increase in accretion expense for 2017 includes an 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 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. The 2016 revisions reflect changes in removal cost estimates, increases in the estimated remaining useful life of certain assets, and decreases in the inflation rate and discount rates used in the annual review process.