Segment Information (Reconciliation Of Other Significant Reconciling Items From Segments To Consolidated) (Details) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Segment Information
Segment Adjusted EBITDA	$ 159,674	[1]	$ 140,580	[1]	$ 314,312	[1]	$ 270,277	[1]
General and administrative	(13,002)		(11,628)		(25,422)		(22,329)
Depreciation, depletion and amortization	(39,100)		(35,677)		(76,962)		(71,973)
Interest expense, net	(9,069)		(7,391)		(18,274)		(14,935)
Income tax expense	(325)		(423)		(96)		(591)
NET INCOME	$ 98,178		$ 85,461		$ 193,558		$ 160,449

[1] Segment Adjusted EBITDA is defined as net income before net interest expense, income taxes, depreciation, depletion and amortization and general and administrative expenses. Management therefore is able to focus solely on the evaluation of segment operating profitability as it relates to our revenues and operating expenses, which are primarily controlled by our segments. Consolidated Segment Adjusted EBITDA is reconciled to net income as follows (in thousands):