Oil and Gas Properties (Income (Loss) From Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations, net of tax	$ 44	$ 4,503		$ 1,073		$ 95,572
Energy Resource Technology GOM, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		119,124		48,847	[1]	447,142
Production (lifting) costs		47,364		16,017	[1]	124,633
Exploration expense		623		3,514	[1]	2,469
Depreciation, depletion, amortization and accretion		38,697		1,226	[1]	126,269
Proved property impairment and abandonment		4,602		(152)	[1]	11,919
Loss on sale of oil and gas properties						1,714
Hedge ineffectiveness and non-hedge gain on commodity derivative contracts		9,427				1,697
Selling, general and administrative expense		3,252		1,229	[1]	9,535
Net interest expense and other		6,959	[2]	2,732	[1],[2]	21,209	[2]
Total costs		110,924		24,566	[1]	299,445
Pretax income from discontinued operations		8,200		24,281	[1]	147,697
Income tax provision		3,697		8,499	[1]	52,125
Income from operations of discontinued operations		4,503		15,782	[1]	95,572
Loss on sale of business, net of tax				(14,709)	[1]
Income from discontinued operations, net of tax		$ 4,503		$ 1,073	[1]	$ 95,572

[1] Results for 2013 primarily reflect the operating results from January 1, 2013 through February 6, 2013 when ERT was sold. There were no material results of operations for our former oil and gas segment subsequent to the sale of ERT.

[2] Net interest expense of $2.7 million for the nine-month period ended September 30, 2013, and $6.9 million and $20.9 million for the three- and nine-month periods ended September 30, 2012, respectively, was allocated to ERT primarily consisting of 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 repaid upon the disposition of ERT.