Oil and Gas Properties (Income (Loss) From Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations, net of tax	$ 1,058		$ 48,853
Helix [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations, net of tax	(14,724)
Energy Resource Technology GOM, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	48,847	[1]	178,085
Production (lifting) costs	16,017	[1]	37,020
Exploration expense	3,514	[1]	754
Depreciation, depletion, amortization and accretion	1,226	[1]	47,843
Proved property impairment and abandonment charges (credits)	(152)	[1]	3,241
Loss on sale of oil and gas properties			1,478
Results Of Operations Gain on oil and gas derivative contracts			2,339
Selling and administrative expense	1,229	[1]	3,281
Net interest expense and other	2,732	[1],[2]	7,277	[2]
Total costs	24,566	[1]	103,233
Pretax income from discontinued operations	24,281	[1]	74,852
Income tax provision	8,499	[1]	25,999
Income from operations of discontinued operations	15,782	[1]	48,853
Loss on sale of business, net of tax	(14,724)	[1]
Income from discontinued operations, net of tax	$ 1,058	[1]	$ 48,853

[1] Results for the first quarter of 2013 were through February 6, 2013 when ERT was sold.

[2] Net interest expense of $2.7 million and $7.2 million for the three-month periods ended March 31, 2013 and 2012, respectively, was allocated to ERT primarily based on interest associated with indebtedness directly attributed to the substantial oil and gas acquisition made in 2006. This includes interest related to debt required to be paid upon the disposition of ERT.