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Asset Retirement Obligations (ARO) (Tables)

12 Months Ended

Dec. 31, 2015

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.

		December 31,
(Thousands of dollars)		2015				2014
Balance at beginning of period		$	22,245			$	17,130
Accretion expense		1,521				1,200
Liabilities incurred		579				3,915
Balance at end of period		$	24,345			$	22,245

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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://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

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