Income Taxes (Schedule Of Deferred Tax Assets And Deferred Tax Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Foreign tax credit carryforward		$ 174,054
Asset retirement obligations	47,860	50,886
Other	82,828	78,014
Total deferred tax assets	130,688	302,954
Valuation allowances		(6,632)
Net deferred tax assets	130,688	296,322
Oil and gas properties, principally due to differences in basis, depletion and the deduction of intangible drilling costs for tax purposes	(1,692,317)	(1,663,343)
Other property and equipment, principally due to the deduction of bonus depreciation for tax purposes	(102,351)	(58,866)
State taxes and other	(191,621)	(117,685)
Net deferred hedge gains	(144,558)	(52,232)
Total deferred tax liabilities	(2,130,847)	(1,892,126)
Net deferred tax liability	(2,000,159)	(1,595,804)
Deferred income taxes	77,005	156,650
Current deferred income tax asset	77,005	156,650
Deferred income taxes		1,144
Current deferred income tax liability		(1,144)
Deferred income taxes	2,077,164	1,751,310
Non-current deferred income tax liability	$ (2,077,164)	$ (1,751,310)