Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	Aug. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 6,639,330	$ 8,355,728	$ 14,368,122	$ 17,855,196
Operating earnings	(91,803)	74,869	168,011	504,929
Loss (gain) on investments	(3,050)	(2,199)	(8,722)	(5,074)
Interest expense, net	15,713	10,771	22,706	32,677
Equity (income) loss from investments	(28,004)	(24,169)	(59,366)	(48,798)
Income (loss) before income taxes	(76,462)	90,466	213,393	526,124
Intersegment revenues	0	0	0	0
Acquisition of property, plant and equipment			428,290	549,930
Depreciation and amortization			207,302	168,306
Total assets	17,825,008	16,114,624	17,825,008	16,114,624	$ 15,228,312
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	1,134,148	1,947,297	2,840,061	4,965,750
Operating earnings	(69,299)	4,244	111,213	287,147
Loss (gain) on investments	0	0	0	0
Interest expense, net	(4,808)	(7,075)	(16,410)	(3,068)
Equity (income) loss from investments	(1,364)	(736)	(2,187)	(1,076)
Income (loss) before income taxes	(63,127)	12,055	129,810	291,291
Intersegment revenues	(67,208)	(101,581)	(174,311)	(280,520)
Acquisition of property, plant and equipment			228,351	307,028
Depreciation and amortization			86,512	71,112
Total assets	4,404,693	4,347,109	4,404,693	4,347,109
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	5,580,450	6,503,348	11,694,706	13,143,319
Operating earnings	(21,818)	72,143	53,173	224,031
Loss (gain) on investments	(42)	0	(5,714)	(2,875)
Interest expense, net	7,992	15,485	22,962	31,005
Equity (income) loss from investments	1,355	(4,443)	(2,221)	(4,463)
Income (loss) before income taxes	(31,123)	61,101	38,146	200,364
Intersegment revenues	(29,963)	(9,149)	(33,016)	(9,149)
Acquisition of property, plant and equipment			160,031	216,418
Depreciation and amortization			111,040	90,714
Total assets	7,710,441	8,354,500	7,710,441	8,354,500
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings	(5,759)	0	(5,759)	0
Loss (gain) on investments	0	0	0	0
Interest expense, net	4,737	0	4,737	0
Equity (income) loss from investments		0	(11,855)	0
Income (loss) before income taxes	1,359	0	1,359	0
Intersegment revenues	0	0	0	0
Acquisition of property, plant and equipment			0	0
Depreciation and amortization			0	0
Total assets	2,812,849	0	2,812,849	0
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	23,201	15,813	43,096	35,796
Operating earnings	5,073	(1,518)	9,384	(6,249)
Loss (gain) on investments	(3,008)	(2,199)	(3,008)	(2,199)
Interest expense, net	7,792	2,361	11,417	4,740
Equity (income) loss from investments	(16,140)	(18,990)	(43,103)	(43,259)
Income (loss) before income taxes	16,429	17,310	44,078	34,469
Intersegment revenues	(1,298)	0	(2,414)	0
Acquisition of property, plant and equipment			39,908	26,484
Depreciation and amortization			9,750	6,480
Total assets	2,897,025	3,413,015	2,897,025	3,413,015
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(98,469)	$ (110,730)	(209,741)	(289,669)
Operating earnings	0		0	0
Loss (gain) on investments	0	$ 0	0	0
Interest expense, net	0	0	0	0
Equity (income) loss from investments	0	0	0	0
Income (loss) before income taxes	0	0	0	0
Intersegment revenues	98,469	110,730	209,741	289,669
Acquisition of property, plant and equipment			0	0
Depreciation and amortization			0	0
Total assets	$ 0	$ 0	$ 0	$ 0