Discontinued Operations (Components Of Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Discontinued Operations [Abstract]
Oil and gas	$ 19,592		$ 43,531
Interest and other	20		4,935
Gain (loss) on disposition of assets, net	(23)	[1]	649,872	[1]
Total revenues and other income from discontinued operations	19,589		698,338
Oil and gas production	790		3,222
Depletion, depreciation and amortization		[1]	13,692	[1]
Exploration and abandonments	84		2,712
General and administrative	1,120		6,815
Accretion of discount on asset retirement obligations	652	[1]	692	[1]
Interest	(75)
Other	(397)		1,202
Total costs and expenses from discontinued operations	2,174		28,335
Income from discontinued operations before income taxes	17,415		670,003
Current tax provision	(5,405)		(13,892)
Deferred tax provision	(1,315)	[1]	(236,229)	[1]
Income from discontinued operations	$ 10,695		$ 419,882

[1] Represents the significant noncash components of discontinued operations.