Correction of immaterial errors (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold	$ 7,479,076	$ 8,429,026	$ 21,346,376	$ 25,446,550
Gross profit	317,512	311,879	818,334	1,149,551
Operating earnings (loss)	148,060	146,538	316,071	651,467
Interest expense, net	26,692	10,780	49,398	43,457
Income (loss) before income taxes	$ 194,521	170,508	407,914	696,632
Depreciation and amortization			324,952	256,073
Accounts payable and accrued expenses			(72,161)	(285,931)
Net Cash Provided by (Used in) Operating Activities			262,425	(26,511)
Acquisition of property, plant and equipment			(557,689)	(858,500)
Expenditures for Major Repairs			(19,338)	(130,302)
Net Cash Provided by (Used in) Investing Activities			(3,604,361)	(1,319,312)
Principal payments on capital lease obligations				(29,886)
Other financing activities, net			(461)	(250)
Net Cash Provided by (Used in) Financing Activities			$ 2,740,584	316,141
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold		8,430,249		25,450,359
Gross profit		310,656		1,145,742
Operating earnings (loss)		145,315		647,658
Interest expense, net		9,557		39,648
Income (loss) before income taxes		170,508		696,632
Depreciation and amortization				227,323
Accounts payable and accrued expenses				(301,956)
Net Cash Provided by (Used in) Operating Activities				(71,286)
Acquisition of property, plant and equipment				(827,228)
Expenditures for Major Repairs				(145,550)
Net Cash Provided by (Used in) Investing Activities				(1,303,288)
Principal payments on capital lease obligations				0
Other financing activities, net				151
Net Cash Provided by (Used in) Financing Activities				344,892
Scenario, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold		(1,223)		(3,809)
Gross profit		1,223		3,809
Operating earnings (loss)		1,223		3,809
Interest expense, net		1,223		3,809
Income (loss) before income taxes		$ 0		0
Depreciation and amortization				28,750
Accounts payable and accrued expenses				16,025
Net Cash Provided by (Used in) Operating Activities				44,775
Acquisition of property, plant and equipment				(31,272)
Expenditures for Major Repairs				15,248
Net Cash Provided by (Used in) Investing Activities				(16,024)
Principal payments on capital lease obligations				(29,886)
Other financing activities, net				(401)
Net Cash Provided by (Used in) Financing Activities				$ (28,751)