Fair Value (Schedule Of Fair Value Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current Investments, Carrying Amount	$ 193,742	$ 150,135
Non-current Investments, Carrying Amount	1,542,199	2,226,875
Cash and cash equivalents, Carrying Amount	186,665	168,490	539,092	441,340
Non-current debt, Carrying Amount	1,370,845	1,875,571
Redeemable noncontrolling interests, Carrying Value	246,546	235,909
Redeemable noncontrolling interests, Fair Value	246,546	235,909
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, Carrying Amount	186,665	168,490
Commodity contracts, Financial Assets	6,974	3,816
Securities sold not owned	1,626	955
Commodity contracts, Financial Liabilities	4,453	2,802
Redeemable noncontrolling interests, Carrying Value	246,546	235,909
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, Fair Value	186,665	168,490
Commodity contracts, Financial Assets	6,974	3,816
Securities sold not owned	1,626	955
Commodity contracts, Financial Liabilities	4,453	2,802
Redeemable noncontrolling interests, Fair Value	246,546	235,909
Current [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current Investments, Carrying Amount	193,742	150,135
Current Notes receivable, Carrying Amount	1,959	1,675
Current debt, Carrying Amount	411,097	447,612
Current [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value measured on recurring basis	193,742	150,135
Notes receivable, Fair Value	1,959	1,675
Current debt, Fair Value	411,097	447,612
Non-Current [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-current Investments, Carrying Amount	1,542,199	2,226,875
Non-current notes receivable, Carrying Amount	12,998	13,531
Non-current debt, Carrying Amount	1,370,845	1,875,571
Non-Current [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value measured on recurring basis	1,542,199	2,226,875
Notes receivable, Fair Value	12,998	13,531
Non-current debt, Fair Value	$ 1,461,272	$ 1,944,879