Recognized Gains and Losses for Derivative Instruments Not Designated as Hedging Instruments (Detail) (Nondesignated, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ (24,127)	$ 5,354
Commodity derivative contracts | Crude oil and product purchases
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	(38,283)	5,659
Foreign exchange derivative contract | Interest and other income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ 14,156	$ (305)