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Asset Retirement Obligations

12 Months Ended

Dec. 31, 2012

Asset Retirement Obligation [Abstract]

The following table presents the change in our AROs during 2012 and 2011:



	2012			2011
	(Millions of Dollars)

Balance as of January 1	$	55.5		$	52.6
Liabilities Incurred	—			0.6
Liabilities Settled	(14.0		)	(2.2		)
Accretion	2.8			3.0
Cash Flow Revisions	—			1.5
Balance as of December 31	$	44.3		$	55.5

- Definition

The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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