Fair Value Measurements - Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2013	Aug. 31, 2013	Nov. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 390,084	$ 499,890	$ 635,684
Derivative Liability, Fair Value, Gross Liability	407,238	465,066	525,094
Commodity and Freight Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	364,454	468,673	632,544
Derivative Liability, Fair Value, Gross Liability	405,346	458,893	518,377
Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	6,776	7,079	3,140
Derivative Liability, Fair Value, Gross Liability	1,647	5,925	6,234
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory, Current, Fair Value Disclosure
Other Assets, Fair Value Disclosure	112,521	114,084	75,873
Total assets	156,655	179,419	167,271
Contingent Liability, Fair Value DIsclosure
Total liabilities	70,006	65,109	64,544
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity and Freight Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	39,948	58,441	88,258
Derivative Liability, Fair Value, Gross Liability	68,362	59,184	58,310
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset
Derivative Liability, Fair Value, Gross Liability
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	4,186	6,894	3,140
Derivative Liability, Fair Value, Gross Liability	1,644	5,925	6,234
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory, Current, Fair Value Disclosure	1,222,328	1,203,383	2,186,328
Other Assets, Fair Value Disclosure
Total assets	1,568,278	1,637,940	2,730,614
Contingent Liability, Fair Value DIsclosure
Total liabilities	337,232	399,958	460,550
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commodity and Freight Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	324,506	410,233	544,286
Derivative Liability, Fair Value, Gross Liability	336,984	399,710	460,067
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	18,854	24,139
Derivative Liability, Fair Value, Gross Liability	245	248	483
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,590	185
Derivative Liability, Fair Value, Gross Liability	3
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory, Current, Fair Value Disclosure
Other Assets, Fair Value Disclosure
Total assets
Contingent Liability, Fair Value DIsclosure	150,991	134,134	170,621
Total liabilities	150,991	134,134	170,621
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Commodity and Freight Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset
Derivative Liability, Fair Value, Gross Liability
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset
Derivative Liability, Fair Value, Gross Liability
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset
Derivative Liability, Fair Value, Gross Liability
Fair Value, Measurements, Recurring | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventory, Current, Fair Value Disclosure	1,222,328	1,203,383	2,186,328
Other Assets, Fair Value Disclosure	112,521	114,084	75,873
Total assets	1,724,933	1,817,359	2,897,885
Contingent Liability, Fair Value DIsclosure	150,991	134,134	170,621
Total liabilities	558,229	599,201	695,715
Fair Value, Measurements, Recurring | Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity and Freight Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	364,454	468,674	632,544
Derivative Liability, Fair Value, Gross Liability	405,346	458,894	518,377
Fair Value, Measurements, Recurring | Estimate of Fair Value, Fair Value Disclosure [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	18,854	24,139
Derivative Liability, Fair Value, Gross Liability	245	248	483
Fair Value, Measurements, Recurring | Estimate of Fair Value, Fair Value Disclosure [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	6,776	7,079	3,140
Derivative Liability, Fair Value, Gross Liability	$ 1,647	$ 5,925	$ 6,234