Acquisitions (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Aug. 31, 2013
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 97,858	$ 8,074
Goodwill	104,615	88,147	85,100
Energy [Member]
Business Acquisition [Line Items]
Goodwill	1,165	1,165
Energy [Member] | National Cooperative Refinery Association [Member]
Business Acquisition [Line Items]
Accrued liability for contingent crack spread payments related to purchase of noncontrolling interest	140,631
Ag Business [Member]
Business Acquisition [Line Items]
Goodwill	$ 96,552	$ 80,084