Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income (loss) from discontinued operations
Income (loss) from discontinued operations									$ 18,860
Impairment on wholly owned assets									(255,046,000)	(192,179)	(205,897)
Goodwill impairment											14,700
Impairment of long-lived assets									(7,853)	7,500
Gain (loss) on disposal of assets									46,811
Less: income tax expense (benefit)									(98,181)	(62,028)	(85,431)
Income (loss) from discontinued operations, net of tax	(193,985)	(12,226)	121,167	(12,396)	(100,323)	(51,501)	(1,887)	(7,379)	(97,440)	(161,090)	(218,609)
Oil and Gas [Member]
Condensed Statements of Income
Operating revenues and Earnings (losses) from unconsolidated affiliates									125,654	37,615	(57,864)
Income (loss) from discontinued operations
Income (loss) from discontinued operations										(26,139)	(81,678)
Other Operating Segments [Member]
Condensed Statements of Income
Operating revenues and Earnings (losses) from unconsolidated affiliates									29,713	29,739	28,751
Income (loss) from discontinued operations
Income (loss) from discontinued operations									(210)	1,059	(1,636)
Goodwill impairment											(14,689)
Impairment of long-lived assets										(7,460)
Less: income tax expense (benefit)									(2,017)	(1,601)	140
Income (loss) from discontinued operations, net of tax									$ (6,046)	$ (4,800)	$ (16,465)