Put and Call Option Contracts (Detail)	3 Months Ended
	Mar. 31, 2014 gal
Derivative [Line Items]
Total fuel price derivative instruments, gallons	58,471,000	[1]
Unleaded Fuel
Derivative [Line Items]
Total fuel price derivative instruments, gallons	39,504,000	[1]
Diesel
Derivative [Line Items]
Total fuel price derivative instruments, gallons	18,967,000	[1]

[1] The settlement of the put and call option contracts is based upon the New York Mercantile Exchange’s New York Harbor Reformulated Gasoline Blendstock for Oxygenate Blending and the U.S. Department of Energy’s weekly retail on-highway diesel fuel price for the month.