Oil And Gas Properties (Changes In Asset Retirement Obligations) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Oil And Gas Properties [Abstract]
Asset retirement obligations at December 31, 2011	$ 254,391
Liability incurred during the period	(115)
Liability settled during the period	(80,166)
Other revision in estimated cash flows	23,671	[1]
Accretion expense (included in depreciation and amortization)	6,854
Asset retirement obligations at June 30, 2012	$ 204,865

[1] The increased amount of these liabilities includes revisions to both non-producing and producing oil and gas properties. Increases to liabilities associated with non-producing properties include a corresponding cost of sales expense charge within our consolidated condensed statements of operations and comprehensive income while changes in estimates for producing properties are recorded as an increase to the related oil and gas properties property and equipment carrying costs included within our consolidated condensed balance sheet.