Segment Reporting - Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011	Aug. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 11,709,938	$ 9,734,159
Cost of goods sold	11,164,420	9,094,152
Gross profit	545,518	640,007
Marketing, general and administrative	124,482	112,520
Operating earnings	421,036	527,487
Loss (gain) on investments		(38)
Interest, net	67,210	20,807
Equity income from investments	(28,072)	(24,129)
Income before income taxes	381,898	530,847
Intersegment Revenue	0	0
Goodwill	82,904	26,233	81,700
Capital expenditures	138,083	98,901
Depreciation and amortization	57,461	51,645
Total identifiable assets	14,008,197	12,136,689	13,423,151
Energy
Segment Reporting Information [Line Items]
Revenues	3,324,228	3,396,974
Cost of goods sold	2,990,842	2,965,168
Gross profit	333,386	431,806
Marketing, general and administrative	36,471	32,903
Operating earnings	296,915	398,903
Loss (gain) on investments
Interest, net	45,783	3,502
Equity income from investments	(1,884)	(1,890)
Income before income taxes	253,016	397,291
Intersegment Revenue	(133,606)	(130,130)
Goodwill	1,165	1,165
Capital expenditures	90,400	59,716
Depreciation and amortization	28,283	26,429
Total identifiable assets	3,962,703	4,063,388
Ag Business
Segment Reporting Information [Line Items]
Revenues	8,501,741	6,449,821
Cost of goods sold	8,308,115	6,259,871
Gross profit	193,626	189,950
Marketing, general and administrative	70,987	61,843
Operating earnings	122,639	128,107
Loss (gain) on investments		(38)
Interest, net	18,212	13,914
Equity income from investments	(7,947)	(7,162)
Income before income taxes	112,374	121,393
Goodwill	74,841	18,170
Capital expenditures	46,745	37,504
Depreciation and amortization	24,886	20,358
Total identifiable assets	7,489,379	5,359,783
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	17,575	17,494
Cost of goods sold	(931)	(757)
Gross profit	18,506	18,251
Marketing, general and administrative	17,024	17,774
Operating earnings	1,482	477
Loss (gain) on investments
Interest, net	3,215	3,391
Equity income from investments	(18,241)	(15,077)
Income before income taxes	16,508	12,163
Goodwill	6,898	6,898
Capital expenditures	938	1,681
Depreciation and amortization	4,292	4,858
Total identifiable assets	2,556,115	2,713,518
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(133,606)	(130,130)
Cost of goods sold	(133,606)	(130,130)
Gross profit	0	0
Operating earnings	0	0
Income before income taxes	0	0
Intersegment Revenue	$ 133,606	$ 130,130