Property And Equipment, Net (Schedule Of Property And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$ 1,713,827	$ 1,235,487
Accumulated depreciation, depletion and amortization	(561,279)	(397,737)
Proved oil and gas properties, net	1,152,548	837,750
Unproved properties, not being amortized
Unevaluated leasehold and seismic costs	238,833	277,425
Exploratory wells in progress	43,803	70,533
Capitalized interest	41,052	46,471
Total costs not subject to amortization	323,688	394,429
Other property and equipment	17,079	12,835
Accumulated depreciation	(5,641)	(4,097)
Other property and equipment, net	11,438	8,738
TOTAL PROPERTY AND EQUIPMENT, NET	$ 1,487,674	$ 1,240,917