Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligations [Abstract]

Schedule Of Asset Retirement Obligations

	Year Ended December 31
	2011	2010
	(In thousands)
Balance at January 1 (including current portion)	$  343,119	$  310,409
Accretion expense	33,601	26,615
Obligations incurred or acquired	115,019	—
Adjustments to the liability from changes in estimates	11,176	8,934
Liabilities settled	(29,012)	(2,839)
Balance at December 31	$  473,903	$  343,119
Current portion included in accrued expenses	(27,119)	(8,862)
Noncurrent liability	$  446,784	$  334,257