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Asset Retirement Obligations (ARO) (Tables)

9 Months Ended

Sep. 30, 2018

Asset Retirement Obligation Disclosure [Abstract]

Reconciliation of Beginning and Ending Aggregate Carrying Amount of Asset Retirement Obligation

A reconciliation of the beginning and ending aggregate carrying amount of the ARO is shown in the following table.

(Millions of dollars)		September 30, 2018				December 31, 2017
Balance at beginning of period		$	28.2			$	26.2
Accretion expense		1.5				1.8
Settlements of liabilities		(0.3		)		(0.3		)
Liabilities incurred		0.6				0.5
Balance at end of period		$	30.0			$	28.2

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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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