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ASSET RETIREMENT OBLIGATION: (Tables)

6 Months Ended

Jun. 30, 2011

ASSET RETIREMENT OBLIGATION:

Summary of the asset retirement obligation activity

		2011			2010
Balance as of January 1		$	59.1		$	48.9
Changes in estimates		—			8.7
Additions		—			—
Accretion expense		1.7			1.6
Balance as of June 30,		$	60.8		$	59.2

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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
-Topic 410
-SubTopic 30
-Publisher FASB
-Number
-Article
-Subparagraph
-Name Accounting Standards Codification
-Paragraph 5
-Section 50
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859

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