Segment Reporting - Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Aug. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 11,026,121	$ 11,709,938
Cost of goods sold	10,625,205	11,164,420
Gross profit	400,916	545,518
Marketing, general and administrative	133,141	124,482
Operating earnings	267,775	421,036
Interest, net	30,785	67,210
Equity income from investments	(32,678)	(28,072)
Income before income taxes	269,668	381,898
Intersegment Revenue	0	0
Goodwill	85,306	82,904	85,100
Capital expenditures	168,024	138,083
Depreciation and amortization	63,104	57,461
Total identifiable assets	14,615,896	14,252,414	13,504,270
Energy
Segment Reporting Information [Line Items]
Revenues	3,679,234	3,324,228
Cost of goods sold	3,505,340	2,990,842
Gross profit	173,894	333,386
Marketing, general and administrative	33,836	36,471
Operating earnings	140,058	296,915
Interest, net	12,476	45,783
Equity income from investments	(1,308)	(1,884)
Income before income taxes	128,890	253,016
Intersegment Revenue	(157,964)	(133,606)
Goodwill	1,165	1,165
Capital expenditures	92,802	90,400
Depreciation and amortization	32,909	28,283
Total identifiable assets	4,219,036	3,979,166
Ag Business
Segment Reporting Information [Line Items]
Revenues	7,488,088	8,501,741
Cost of goods sold	7,277,829	8,308,115
Gross profit	210,259	193,626
Marketing, general and administrative	85,002	70,987
Operating earnings	125,257	122,639
Interest, net	15,065	18,212
Equity income from investments	(6,477)	(7,947)
Income before income taxes	116,669	112,374
Goodwill	77,243	74,841
Capital expenditures	71,880	46,745
Depreciation and amortization	27,558	24,886
Total identifiable assets	6,802,559	7,688,325
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	16,763	17,575
Cost of goods sold		(931)
Gross profit	16,763	18,506
Marketing, general and administrative	14,303	17,024
Operating earnings	2,460	1,482
Interest, net	3,244	3,215
Equity income from investments	(24,893)	(18,241)
Income before income taxes	24,109	16,508
Goodwill	6,898	6,898
Capital expenditures	3,342	938
Depreciation and amortization	2,637	4,292
Total identifiable assets	3,594,301	2,584,923
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(157,964)	(133,606)
Cost of goods sold	(157,964)	(133,606)
Gross profit	0	0
Operating earnings	0	0
Income before income taxes	0	0
Intersegment Revenue	$ 157,964	$ 133,606