Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2011

Commitments And Contingencies [Abstract]

Schedule Of Changes In Asset Retirement Obligations

(add 000)	2011			2010
Balance at January 1	$	41,079		$	38,779
Accretion expense		2,645			2,464
Liabilities incurred		3,062			495
Liabilities settled		(2,091	)		(392	)
Revisions in estimated cash flows		(1,462	)		(267	)
Balance at December 31	$	43,233		$	41,079

Schedule Of Contractual Purchase Commitments

(add 000)
2012	$	53,745
2013		16,703
2014		17,284
Total	$	87,732