Derivative Financial Instruments and Hedging Activities Derivatives (Details) - USD ($)	3 Months Ended			9 Months Ended
	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	May 31, 2016	May 31, 2015	Aug. 31, 2015
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 532,723,000			$ 532,723,000		$ 443,358,000
Derivative Asset, Fair Value, Gross Asset	587,013,000			587,013,000		513,441,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	54,290,000			54,290,000		70,083,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	422,484,000			422,484,000		389,204,000
Derivative Liability, Fair Value, Gross Liability	486,631,000			486,631,000		470,769,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	9,857,000			9,857,000		11,482,000
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	54,290,000			54,290,000		70,083,000
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net				0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	19,877,000			19,877,000		14,216,000
Derivative Asset, Fair Value, Gross Asset	19,877,000			19,877,000		14,216,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	0			0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0			0		6,058,000
Derivative Liability, Fair Value, Gross Liability	0			0		6,058,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0			0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	0			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	505,430,000			505,430,000		417,670,000
Derivative Asset, Fair Value, Gross Asset	553,048,000			553,048,000		476,071,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	47,618,000			47,618,000		58,401,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	414,865,000			414,865,000		357,169,000
Derivative Liability, Fair Value, Gross Liability	472,340,000			472,340,000		427,052,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	9,857,000			9,857,000		11,482,000
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	47,618,000			47,618,000		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	7,416,000			7,416,000		11,472,000
Derivative Asset, Fair Value, Gross Asset	14,088,000			14,088,000		23,154,000
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet	6,672,000			6,672,000		11,682,000
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	7,604,000			7,604,000		25,916,000
Derivative Liability, Fair Value, Gross Liability	14,276,000			14,276,000		37,598,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0			0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	6,672,000			6,672,000		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	15,000			15,000		61,000
Derivative Liability, Fair Value, Gross Liability	15,000			15,000		61,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0			0		0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet	0			0		0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Purchase and Sales Contracts [Line Items]
Derivative Asset, Notional Amount	820,200,000			820,200,000		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				7,600,000	$ 8,300,000
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			$ 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	$ 5,100,000	$ 5,300,000	$ 6,400,000
Derivatives settled, number	2	2	2