Oil And Gas Properties (Narrative) (Details) (USD $)	3 Months Ended	6 Months Ended			6 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Domestic Oil And Gas Property B Member	Jun. 30, 2012 Non-Domestic Oil And Gas Property [Member]	Jun. 30, 2011 Non-Domestic Oil And Gas Property [Member]	Jun. 30, 2012 Domestic Oil And Gas Property A Member	Jun. 30, 2012 Hurricane Catastrophic Bond [Member]
Abandonment Expense	$ 11,100,000					$ 6,900,000	$ 4,100,000
Oil and gas property impairments	11,573,000	11,573,000
Asset retirement obligation			204,865,000	254,391,000
Capitalized exploration cost			32,800,000					26,900,000
Working interest in oil and gas field					70.00%			50.00%
Prepaid insurance									10,600,000
Future Insurance Expense Q4									2,000,000
Future Insurance Expense Q3									$ 8,400,000