Oil And Gas Properties (Major Classes Of Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	$ 2		$ 2		$ 1
Current assets of discontinued operations	84,000		118,921
Non-current assets of discontinued operations	816,227		905,399
Current asset retirement obligations	2,898	[1]	27,300	[1]
Current liabilities of discontinued operations	182,527		166,975
Non-current liabilities of discontinued operations	147,237		161,208
Energy Resource Technology GOM, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	2		2
Accounts receivable	63,762		90,882
Other current assets	20,236		28,037
Current assets of discontinued operations	84,000		118,921
Property and equipment, net	787,852		871,658
Other assets, net	28,375		33,741
Non-current assets of discontinued operations	816,227		905,399
Accounts payable	110,569		73,124
Accrued liabilities	18,217		27,968
Current asset retirement obligations	53,741		65,883
Current liabilities of discontinued operations	182,527		166,975
Asset retirement obligations	147,237		161,208
Non-current liabilities of discontinued operations	$ 147,237		$ 161,208

[1] Reflects the substantial completion of the abandonment of the Camelot field (Note 3).