Correction of immaterial errors (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold	$ 6,550,326	$ 8,110,084	$ 13,867,300	$ 17,017,524
Gross profit	89,004	245,644	500,822	837,672
Operating earnings	(91,803)	74,869	168,011	504,929
Interest expense, net	15,713	10,771	22,706	32,677
Income (loss) before income taxes	$ (76,462)	90,466	213,393	526,124
Depreciation and amortization			207,302	168,306
Accounts payable and accrued expenses			24,729	(629,850)
Net Cash Provided by (Used in) Operating Activities			319,083	(502,176)
Acquisition of property, plant and equipment			(428,290)	(549,930)
Expenditures for Major Repairs			(19,090)	(7,505)
Net Cash Provided by (Used in) Investing Activities			(3,245,082)	(906,800)
Principal payments on capital lease obligations				(20,191)
Other financing activities, net			3,148	20
Net Cash Provided by (Used in) Financing Activities			$ 2,310,280	535,388
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold		8,111,365		17,020,110
Gross profit		244,363		835,086
Operating earnings		73,588		502,343
Interest expense, net		9,490		30,091
Income (loss) before income taxes		90,466		526,124
Depreciation and amortization				148,784
Accounts payable and accrued expenses				(666,428)
Net Cash Provided by (Used in) Operating Activities				(558,276)
Acquisition of property, plant and equipment				(512,510)
Expenditures for Major Repairs				(8,347)
Net Cash Provided by (Used in) Investing Activities				(870,222)
Principal payments on capital lease obligations				0
Other financing activities, net				(282)
Net Cash Provided by (Used in) Financing Activities				554,910
Scenario, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold		(1,281)		(2,586)
Gross profit		1,281		2,586
Operating earnings		1,281		2,586
Interest expense, net		1,281		2,586
Income (loss) before income taxes		$ 0		0
Depreciation and amortization				19,522
Accounts payable and accrued expenses				36,578
Net Cash Provided by (Used in) Operating Activities				56,100
Acquisition of property, plant and equipment				(37,420)
Expenditures for Major Repairs				842
Net Cash Provided by (Used in) Investing Activities				(36,578)
Principal payments on capital lease obligations				(20,191)
Other financing activities, net				302
Net Cash Provided by (Used in) Financing Activities				$ (19,522)