Property And Equipment, Net (Schedule Of Property And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$ 2,086,461	$ 1,713,827
Accumulated depreciation, depletion and amortization	(656,660)	(561,279)
Proved oil and gas properties, net	1,429,801	1,152,548
Unproved properties, not being amortized
Unevaluated leasehold costs	284,362	238,833
Exploratory wells in progress	30,936	43,803
Capitalized interest	45,236	41,052
Total unproved properties, not being amortized	360,534	323,688
Other property and equipment	18,975	17,079
Accumulated depreciation	(6,448)	(5,641)
Other property and equipment, net	12,527	11,438
TOTAL PROPERTY AND EQUIPMENT, NET	$ 1,802,862	$ 1,487,674