Segment Reporting - Segment Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Segment Reporting Information [Line Items]
Revenues	$ 40,599,286	$ 36,915,834	$ 25,267,931
Cost of goods sold	38,588,143	35,512,988	24,397,410
Gross profit	2,011,143	1,402,846	870,521
Marketing, general and administrative	498,233	438,498	366,582
Operating earnings	1,512,910	964,348	503,939
Loss (gain) on investments	5,465	(126,729)	(29,433)
Interest, net	193,263	74,835	58,324
Equity income from investments	(102,389)	(131,414)	(108,787)
Income before income taxes	1,416,571	1,147,656	583,835
Intersegment Revenue	0	0	0
Goodwill	81,693	26,409	23,038
Capital expenditures	468,611	310,670	324,262
Depreciation and amortization	219,632	220,694	202,922
Total identifiable assets	13,423,151	12,217,010
Energy
Segment Reporting Information [Line Items]
Revenues	12,816,542	11,467,381	8,799,890
Cost of goods sold	11,514,463	10,694,687	8,437,504
Gross profit	1,302,079	772,694	362,386
Marketing, general and administrative	155,786	142,708	123,834
Operating earnings	1,146,293	629,986	238,552
Loss (gain) on investments	4,008	1,027	(269)
Interest, net	122,302	5,829	9,939
Equity income from investments	(7,537)	(6,802)	(5,554)
Income before income taxes	1,027,520	629,932	234,436
Intersegment Revenue	(467,583)	(383,389)	(295,536)
Goodwill	1,165	1,165	1,165
Capital expenditures	294,560	198,692	197,637
Depreciation and amortization	109,496	126,018	118,071
Total identifiable assets	3,684,571	3,883,205
Ag Business
Segment Reporting Information [Line Items]
Revenues	28,181,445	25,767,033	16,715,055
Cost of goods sold	27,544,040	25,204,301	16,258,679
Gross profit	637,405	562,732	456,376
Marketing, general and administrative	273,757	229,369	187,640
Operating earnings	363,648	333,363	268,736
Loss (gain) on investments	1,049	(118,344)	(421)
Interest, net	57,915	57,438	33,039
Equity income from investments	(22,737)	(40,482)	(31,248)
Income before income taxes	327,421	434,751	267,366
Goodwill	73,630	18,346	14,975
Capital expenditures	168,825	107,866	122,468
Depreciation and amortization	92,538	79,231	69,170
Total identifiable assets	6,816,809	5,276,537
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	68,882	64,809	48,522
Cost of goods sold	(2,777)	(2,611)	(3,237)
Gross profit	71,659	67,420	51,759
Marketing, general and administrative	68,690	66,421	55,108
Operating earnings	2,969	999	(3,349)
Loss (gain) on investments	408	(9,412)	(28,743)
Interest, net	13,046	11,568	15,346
Equity income from investments	(72,115)	(84,130)	(71,985)
Income before income taxes	61,630	82,973	82,033
Goodwill	6,898	6,898	6,898
Capital expenditures	5,226	4,112	4,157
Depreciation and amortization	17,598	15,445	15,681
Total identifiable assets	2,921,771	3,057,268
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(467,583)	(383,389)	(295,536)
Cost of goods sold	(467,583)	(383,389)	(295,536)
Gross profit	0	0	0
Marketing, general and administrative
Operating earnings	0	0	0
Income before income taxes	0	0	0
Intersegment Revenue	$ 467,583	$ 383,389	$ 295,536