Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2014

Asset Retirement Obligation Disclosure [Abstract]

Change in Asset Retirement Obligations

The following table presents the change in our AROs during 2014 and 2013:

	2014			2013
	(Millions of Dollars)
Balance as of January 1	$	42.3		$	44.3
Liabilities Settled	(1.1		)	(4.4		)
Accretion	2.4			2.4
Balance as of December 31	$	43.6		$	42.3