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Asset retirement obligations (“ARO”) (Tables)

9 Months Ended

Sep. 30, 2013

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Change in Asset Retirement Obligations

The reconciliation of the changes in the asset retirement obligations is presented below:

	Nine months ended September 30, 2013			Year ended December 31, 2012
Beginning balance, ARO liability	$	16,124		$	15,171
Additional ARO liability incurred	1,648			1,166
ARO liabilities settled	(1,493		)	(1,380		)
Accretion expense	1,334			1,167
Additional ARO liability from Sebree acquisition	10,106			—
Ending balance, ARO liability	$	27,719		$	16,124

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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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