Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015	Aug. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 7,796,588	$ 8,740,905	$ 22,164,710	$ 26,596,101
Operating earnings (loss)	148,060	146,538	316,071	651,467
Loss (gain) on investments	(700)	0	(9,422)	(5,074)
Interest expense, net	26,692	10,780	49,398	43,457
Equity (income) loss from investments	(72,453)	(34,750)	(131,819)	(83,548)
Income (loss) before income taxes	194,521	170,508	407,914	696,632
Intersegment revenues	0	0	0	0
Acquisition of property, plant and equipment			557,689	858,500
Depreciation and amortization			324,952	256,073
Total assets	18,258,094	15,852,982	18,258,094	15,852,982	$ 15,228,312
Energy [Member]
Segment Reporting Information [Line Items]
Revenues	1,322,624	1,732,192	4,162,685	6,697,942
Operating earnings (loss)	103,614	75,498	214,827	362,645
Loss (gain) on investments	0	0	0	0
Interest expense, net	(4,487)	(7,479)	(20,897)	(10,547)
Equity (income) loss from investments	(1,300)	(364)	(3,487)	(1,440)
Income (loss) before income taxes	109,401	83,341	239,211	374,632
Intersegment revenues	(76,114)	(94,092)	(250,425)	(374,612)
Acquisition of property, plant and equipment			305,694	494,681
Depreciation and amortization			139,391	107,910
Total assets	4,524,718	4,625,773	4,524,718	4,625,773
Ag [Member]
Segment Reporting Information [Line Items]
Revenues	6,526,714	7,088,072	18,221,420	20,231,391
Operating earnings (loss)	24,432	69,215	77,605	293,247
Loss (gain) on investments	(881)	0	(6,595)	(2,875)
Interest expense, net	7,045	15,494	30,007	46,500
Equity (income) loss from investments	(5,931)	(7,964)	(8,152)	(12,427)
Income (loss) before income taxes	24,199	61,685	62,345	262,049
Intersegment revenues	(3,016)	(3,017)	(36,032)	(12,166)
Acquisition of property, plant and equipment			205,517	309,384
Depreciation and amortization			168,596	137,712
Total assets	7,959,387	8,141,681	7,959,387	8,141,681
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating earnings (loss)	253	0	(5,506)	0
Loss (gain) on investments	0	0	0	0
Interest expense, net	16,549	0	21,286	0
Equity (income) loss from investments	(41,257)	0	(53,112)	0
Income (loss) before income taxes	24,961	0	26,320	0
Intersegment revenues	0	0	0	0
Acquisition of property, plant and equipment			0	0
Depreciation and amortization			0	0
Total assets	2,854,201	0	2,854,201	0
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	25,114	17,750	68,210	53,546
Operating earnings (loss)	19,761	1,825	29,145	(4,425)
Loss (gain) on investments	181	0	(2,827)	(2,199)
Interest expense, net	7,585	2,765	19,002	7,504
Equity (income) loss from investments	(23,965)	(26,422)	(67,068)	(69,681)
Income (loss) before income taxes	35,960	25,482	80,038	59,951
Intersegment revenues	1,266	0	(1,148)	0
Acquisition of property, plant and equipment			46,478	54,435
Depreciation and amortization			16,965	10,451
Total assets	2,919,788	3,085,528	2,919,788	3,085,528
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(77,864)	(97,109)	(287,605)	(386,778)
Operating earnings (loss)	0	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	77,864	97,109	287,605	386,778
Acquisition of property, plant and equipment			0	0
Depreciation and amortization			0	0
Total assets	$ 0	$ 0	$ 0	$ 0