Derivative Financial Instruments and Hedging Activities Derivatives (Details) - USD ($)	3 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Aug. 31, 2015
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 401,634,000		$ 443,358,000
Derivative Asset, Fair Value, Gross Asset	443,857,000		513,441,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	42,223,000		70,083,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	309,543,000		389,204,000
Derivative Liability, Fair Value, Gross Liability	370,215,000		470,769,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	18,449,000		11,482,000
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	42,223,000		70,083,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	14,578,000		14,216,000
Derivative Asset, Fair Value, Gross Asset	14,578,000		14,216,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	5,267,000		6,058,000
Derivative Liability, Fair Value, Gross Liability	5,267,000		6,058,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	0		0
Not Designated as Hedging Instrument [Member] | Commodity and Freight Derivatives [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	375,772,000		417,670,000
Derivative Asset, Fair Value, Gross Asset	404,915,000		476,071,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	29,143,000		58,401,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	294,786,000		357,169,000
Derivative Liability, Fair Value, Gross Liability	342,378,000		427,052,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	18,449,000		11,482,000
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	29,143,000		58,401,000
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	11,284,000		11,472,000
Derivative Asset, Fair Value, Gross Asset	24,364,000		23,154,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	13,080,000		11,682,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	9,471,000		25,916,000
Derivative Liability, Fair Value, Gross Liability	22,551,000		37,598,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	13,080,000		11,682,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Purchase and Sales Contracts [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	19,000		61,000
Derivative Liability, Fair Value, Gross Liability	19,000		61,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	0		0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Notional Amount	731,700,000		$ 1,300,000,000
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Purchase and Sales Contracts [Line Items]
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	2,300,000	$ 8,200,000
Fair Value Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Notional Amount	420,000,000
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Notional Amount	300,000,000
Cash paid to settle derivative	$ 6,400,000
Derivatives settled, number	2