Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018	Aug. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 6,483,539	$ 6,980,153	$ 14,967,828	$ 15,012,037
Operating earnings (loss)	249,645	(41,243)	564,143	142,690
(Gain) loss on disposal of business	0	(7,705)	(1,412)	(7,705)
Interest Expense	41,269	40,176	80,177	80,878
Other (income) loss	(11,763)	(12,544)	(35,485)	(38,739)
Equity (income) loss from investments	(41,716)	(39,441)	(108,224)	(77,803)
Income (loss) before income taxes	261,855	(21,729)	629,087	186,059
Total assets	16,936,174		16,936,174		$ 16,381,178
Energy
Segment Reporting Information [Line Items]
Revenues, including intersegment revenues	1,570,968	1,771,809	3,881,048	3,845,809
Revenues	1,474,777		3,636,065
Operating earnings (loss)	301,721	25,318	537,360	149,349
Interest Expense	(1,652)	2,629	2,585	8,264
Other (income) loss	(2,217)	(1,122)	(3,203)	(2,010)
Equity (income) loss from investments	(995)	(660)	(1,068)	(1,812)
Income (loss) before income taxes	306,585	24,471	539,046	144,907
Total assets	4,349,524		4,349,524
Ag
Segment Reporting Information [Line Items]
Revenues, including intersegment revenues	4,998,137	5,300,503	11,306,851	11,381,530
Revenues	4,994,545		11,299,942
Operating earnings (loss)	(47,129)	(53,125)	32,998	7,784
Interest Expense	25,398	22,784	46,398	40,388
Other (income) loss	(10,257)	(9,112)	(31,245)	(32,698)
Equity (income) loss from investments	128	(5,567)	1,337	(13,821)
Income (loss) before income taxes	(62,398)	(53,525)	17,920	21,620
Total assets	6,969,518		6,969,518
Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues, including intersegment revenues	0	0	0	0
Operating earnings (loss)	(9,880)	(7,239)	(15,008)	(10,374)
Interest Expense	15,342	12,676	29,021	25,948
Other (income) loss	(392)	(433)	(1,963)	(2,171)
Equity (income) loss from investments	(35,542)	(24,012)	(76,457)	(44,347)
Income (loss) before income taxes	10,712	4,530	34,391	10,196
Total assets	2,745,652		2,745,652
Corporate and Other
Segment Reporting Information [Line Items]
Revenues, including intersegment revenues	16,694	13,168	35,761	31,943
Revenues	14,217		31,821
Operating earnings (loss)	4,933	(6,197)	8,793	(4,069)
Interest Expense	3,299	2,665	4,062	7,245
Other (income) loss	(15)	(2,455)	(963)	(2,827)
Equity (income) loss from investments	(5,307)	(9,202)	(32,036)	(17,823)
Income (loss) before income taxes	6,956	2,795	37,730	9,336
Total assets	2,871,480		2,871,480
Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	(102,260)	(105,327)	(255,832)	(247,245)
Operating earnings (loss)	0		0	0
Interest Expense	(1,118)	(578)	(1,889)	(967)
Other (income) loss	1,118	578	1,889	967
Equity (income) loss from investments	0	0	0	0
Income (loss) before income taxes	0	0	0	0
Total assets	0		0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Energy
Segment Reporting Information [Line Items]
Revenues	(96,191)	(100,010)	(244,983)	(234,864)
Intersegment Eliminations [Member] | Ag
Segment Reporting Information [Line Items]
Revenues	(3,592)	(3,575)	(6,909)	(7,608)
Intersegment Eliminations [Member] | Nitrogen Production [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	(2,477)	(1,742)	(3,940)	(4,773)
Intersegment Eliminations [Member] | Reconciling Amounts
Segment Reporting Information [Line Items]
Revenues	$ 102,260	105,327	255,832	247,245
Operating Segments [Member] | Energy
Segment Reporting Information [Line Items]
(Gain) loss on disposal of business		0	0	0
Operating Segments [Member] | Ag
Segment Reporting Information [Line Items]
(Gain) loss on disposal of business		(7,705)	(1,412)	(7,705)
Operating Segments [Member] | Nitrogen Production [Member]
Segment Reporting Information [Line Items]
(Gain) loss on disposal of business		0	0	0
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
(Gain) loss on disposal of business		0	0	0
Reconciling Amounts
Segment Reporting Information [Line Items]
(Gain) loss on disposal of business		$ 0	$ 0	$ 0