Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 34,582,442	$ 42,664,033	$ 44,479,857
Operating earnings	715,412	1,049,948	1,225,161
(Gain) loss on investments	(5,239)	(114,162)	(182)
Interest, net	60,333	140,253	236,699
Equity (income) loss from investments	(107,850)	(107,446)	(97,350)
Income before income taxes	768,168	1,131,303	1,085,994
Sales	0	0	0
Capital expenditures	1,186,790	919,076	619,883
Depreciation and amortization	355,422	306,247	276,580
Total assets	15,228,312	15,296,104
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	8,694,326	12,181,212	11,431,423
Operating earnings	523,451	793,924	958,468
(Gain) loss on investments	0	0	0
Interest, net	(12,350)	69,522	148,931
Equity (income) loss from investments	(2,330)	(4,014)	(1,357)
Income before income taxes	538,131	728,416	810,894
Sales	(483,989)	(600,433)	(481,465)
Capital expenditures	696,825	539,170	429,230
Depreciation and amortization	148,292	137,408	123,898
Total assets	4,624,471	4,457,563
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	26,311,350	31,022,507	33,471,977
Operating earnings	190,860	249,944	263,757
(Gain) loss on investments	(2,875)	(1,949)	(27)
Interest, net	56,380	60,742	76,138
Equity (income) loss from investments	(12,293)	(22,279)	(15,194)
Income before income taxes	149,648	213,430	202,840
Sales	(11,403)	(9,960)	(11,316)
Capital expenditures	417,950	329,613	183,619
Depreciation and amortization	192,438	157,102	136,556
Total assets	7,814,689	6,949,617
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	74,828	73,827	71,596
Operating earnings	1,101	6,080	2,936
(Gain) loss on investments	(2,364)	(112,213)	(155)
Interest, net	16,303	9,989	11,630
Equity (income) loss from investments	(93,227)	(81,153)	(80,799)
Income before income taxes	80,389	189,457	72,260
Sales	(2,670)	(3,120)	(2,358)
Capital expenditures	72,015	50,293	7,034
Depreciation and amortization	14,692	11,737	16,126
Total assets	2,789,152	3,888,924
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(498,062)	(613,513)	(495,139)
Operating earnings	0	0	0
(Gain) loss on investments	0	0	0
Interest, net	0	0	0
Equity (income) loss from investments	0	0	0
Income before income taxes	0	0	0
Sales	498,062	613,513	495,139
Capital expenditures	0	0	0
Depreciation and amortization	0	0	$ 0
Total assets	$ 0	$ 0