XML 95 R39.htm IDEA: XBRL DOCUMENT v3.8.0.1

Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2017

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 2017 and 2016, were as follows:

		2017			2016
(Dollars in millions)
Balance at beginning of year		$	266		$	243
	Additional liabilities accrued		1			1
	Revisions in estimated cash outflows		(1)			7
	Acquisition of assets		1			–
	Disposition of assets		(1)			(1)
	Accretion expense		17			16
Balance at end of year		$	283		$	266

X

- References

No definition available.

+ Details

Name:	us-gaap_AssetRetirementObligationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- 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://www.xbrl.org/2003/role/presentationRef
-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

+ Details

Name:	us-gaap_ScheduleOfChangeInAssetRetirementObligationTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration