Derivatives (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	$ 78,203	$ 68,065
Derivative liabilities	69,547	57,920
Derivatives designated as hedging instruments
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	1,139	550
Derivative liabilities	2,284	1,540
Derivatives designated as hedging instruments | Commodity contracts | Other current assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	991	528
Derivative liabilities	2,284	1,519
Derivatives designated as hedging instruments | Commodity contracts | Accrued expenses and other current liabilities
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets		22
Derivative liabilities		21
Derivatives designated as hedging instruments | Foreign currency contracts | Other current assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	148
Derivatives not designated as hedging instruments
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	77,064	67,515
Derivative liabilities	67,263	56,380
Derivatives not designated as hedging instruments | Commodity contracts | Other current assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	67,533	59,185
Derivative liabilities	41,410	37,713
Derivatives not designated as hedging instruments | Commodity contracts | Non-current other assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	1,423	2,065
Derivative liabilities	47	2
Derivatives not designated as hedging instruments | Commodity contracts | Accrued expenses and other current liabilities
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	5,776	3,231
Derivative liabilities	20,927	16,434
Derivatives not designated as hedging instruments | Commodity contracts | Other long-term liabilities
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	46	40
Derivative liabilities	1,034	1,213
Derivatives not designated as hedging instruments | Foreign currency contracts | Other current assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	741	1,912
Derivative liabilities	595	413
Derivatives not designated as hedging instruments | Foreign currency contracts | Non-current other assets
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets		1,082
Derivative liabilities		481
Derivatives not designated as hedging instruments | Foreign currency contracts | Accrued expenses and other current liabilities
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative assets	1,545
Derivative liabilities	3,151	124
Derivatives not designated as hedging instruments | Foreign currency contracts | Other long-term liabilities
Information about derivative instruments measured at fair value and their locations on the consolidated balance sheet
Derivative liabilities	$ 99