XML 86 R39.htm IDEA: XBRL DOCUMENT v3.22.4

ASSET RETIREMENT OBLIGATION: (Tables)

12 Months Ended

Dec. 31, 2022

ASSET RETIREMENT OBLIGATION:

Summary of asset retirement obligation activity

The following table summarizes the asset retirement obligation activity for the years ended December 31, 2021 and 2020 (in millions):

​	​	​	​	​	​	​
​		2022			2021
Balance as of January 1	​	$	562.9	​	$	545.0
Changes in estimates	​		(10.8)	​		—
Additions	​		11.9	​		​
Closure payments	​		(7.1)	​		(5.6)
Accretion expense	​		28.4	​		23.5
Balance as of December 31,	​	$	585.3	​	$	562.9

X

- References

No definition available.

+ Details

Name:	us-gaap_AssetRetirementObligationDisclosureAbstract
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/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

+ Details

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