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Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2018

Asset Retirement Obligation [Abstract]

Asset retirement obligations

The results of the reviews (identified as Revisions in estimated cash outflows) and other changes in asset retirement obligations during 2018 and 2017, were as follows:

	2018				2017
(Dollars in millions)
Balance at beginning of year	$	283			$	266
Additional liabilities accrued	2				1
Revisions in estimated cash outflows	6				(1		)
Acquisition of assets	—				1
Disposition of assets	(1		)		(1		)
Accretion expense	18				17
Transferred to Liabilities held for sale	(1		)		—
Balance at end of year	$	307			$	283

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- References

No definition available.

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- Definition

Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859

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