Gains and Losses for Derivative Instruments Not Designated as Hedging Instruments (Detail) (Nondesignated, USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ 5	$ 12,259	$ 10,514	$ 28,596
Commodity Derivative Contracts | Crude Oil and Product Purchases
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	7,381	(1,695)	5,900	(1,085)
Foreign Exchange Derivative Contracts | Interest and other income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ (7,376)	$ 13,954	$ 4,614	$ 29,681