Recognized Gains and Losses for Derivative Instruments Not Designated as Hedging Instruments (Detail) (Nondesignated, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ (33,656)	$ 5	$ (22,196)	$ 10,514
Commodity derivative contracts | Crude oil and product purchases
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	(40,241)	7,381	(37,978)	5,900
Foreign exchange derivative contract | Interest and other income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ 6,585	$ (7,376)	$ 15,782	$ 4,614