Supplemental Oil And Gas Disclosures (Results Of Operations For Oil And Natural Gas Producing Activities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009 contracts
Supplemental Oil And Gas Disclosures [Abstract]
Revenues	$ 330,422		$ 128,927		$ 37,755
Production costs	67,937		28,350		12,501
Depreciation, depletion and amortization	74,101		37,583		16,592
Exploration costs	1,685		297		1,019
Rig termination		[1]		[1]	3,000	[1]
Impairment of oil and gas properties	3,610		11,967		6,233
Gain (Loss) on Sale of Property	(207)				1,455
Loss on sale of properties	(207)				1,455
Loss (gain) on sale of properties	207				(1,455)
Income tax expenses	64,009		17,756
Results of operations for oil and gas producing activities	$ 118,873		$ 32,974		$ (135)
Number of drilling rig contracts terminated during the period.					2

[1] During the first quarter of 2009, we paid a total of $3.0 million in rig termination expenses in connection with early termination of two drilling rig contracts entered into in 2008. We did not have any rig termination expenses during the years ended December 31, 2011 and 2010.