Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015
Cash flows from operating activities:
Net earnings (loss)	$ 59,532	$ 70,325	$ 224,461	$ 167,353
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(10,143)	(5,245)
Depreciation and amortization			41,681	33,258
Net (gain) loss on disposition of equipment	(311)	(720)	(11,326)	(924)
Stock based compensation expense	8,300	6,000	19,055	13,176
Noncontrolling interest adjustments			837	20,371
Other			564	1,008
Decrease (increase) in assets:
Accounts receivable, net			(14,333)	(8,769)
Inventories			(15,346)	(124,906)
Leased railcars for syndication			28,823	(90,914)
Other			(5,191)	(1,666)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(88,707)	23,135
Deferred revenue			24,303	3,680
Net cash provided by (used in) operating activities			194,678	29,557
Cash flows from investing activities:
Proceeds from sales of assets			88,707	4,628
Capital expenditures			(51,707)	(75,892)
Decrease (increase) in restricted cash			200	228
Investment in and net advances to unconsolidated affiliates			(9,088)	(29,923)
Cash distribution from unconsolidated affiliates			5,338	715
Net cash provided by (used in) investing activities			33,450	(100,244)
Cash flows from financing activities:
Net changes in revolving notes with maturities of 90 days or less			(49,000)	73,000
Proceeds from revolving notes with maturities longer than 90 days				42,563
Repayments of revolving notes with maturities longer than 90 days			(1,888)	(36,137)
Repayments of notes payable			(19,461)	(5,504)
Debt issuance costs			(4,160)
Repurchase of stock			(33,498)	(48,451)
Dividends			(17,362)	(12,069)
Decrease in restricted cash				11,000
Cash contribution to joint venture partner			(62,710)	(12,489)
Investment by joint venture partner			5,400
Excess tax benefit from restricted stock awards			2,786	2,964
Other			(7)
Other			(7)	(248)
Net cash provided by (used in) financing activities			(179,900)	14,629
Effect of exchange rate changes			(6,718)	(6,075)
Increase (decrease) in cash and cash equivalents			41,510	(62,133)
Beginning of period			172,930	184,916
End of period	214,440	122,783	214,440	122,783
Parent
Cash flows from operating activities:
Net earnings (loss)	35,352	42,811	149,653	125,948
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			15,000	(138)
Depreciation and amortization			2,059	1,484
Stock based compensation expense			19,055	13,176
Other				43
Decrease (increase) in assets:
Accounts receivable, net			45,735	50
Other			(1,715)	20,641
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(48,102)	(3,824)
Deferred revenue			32,732	(122)
Net cash provided by (used in) operating activities			214,417	157,258
Cash flows from investing activities:
Capital expenditures			(2,796)	(2,424)
Investment in and net advances to unconsolidated affiliates			(176,356)	(245,594)
Cash distribution from unconsolidated affiliates			5,338	715
Net cash provided by (used in) investing activities			(173,814)	(247,303)
Cash flows from financing activities:
Net changes in revolving notes with maturities of 90 days or less			(49,000)	73,000
Repayments of notes payable			(13,981)	(5)
Debt issuance costs			(4,160)
Intercompany advances			75,289	(18,997)
Repurchase of stock			(33,498)	(48,451)
Dividends			(17,362)	(12,069)
Excess tax benefit from restricted stock awards			2,786	2,964
Other				(248)
Net cash provided by (used in) financing activities			(39,926)	(3,806)
Effect of exchange rate changes			1,505
Increase (decrease) in cash and cash equivalents			2,182	(93,851)
Beginning of period			53,535	149,747
End of period	55,717	55,896	55,717	55,896
Combined Guarantor Subsidiaries
Cash flows from operating activities:
Net earnings (loss)	34,690	39,625	136,184	138,166
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(18,235)	(8,000)
Depreciation and amortization			23,314	19,909
Net (gain) loss on disposition of equipment	(308)	(724)	(10,950)	(927)
Other			(32)	105
Decrease (increase) in assets:
Accounts receivable, net			27,389	(10,046)
Inventories			(82,518)	(39,279)
Leased railcars for syndication			36,802	(109,324)
Other			(1,666)	763
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(59,664)	25,612
Deferred revenue			(8,710)	4,078
Net cash provided by (used in) operating activities			41,914	21,057
Cash flows from investing activities:
Proceeds from sales of assets			88,697	4,623
Capital expenditures			(18,480)	(18,807)
Decrease (increase) in restricted cash			201	229
Investment in and net advances to unconsolidated affiliates			(26,977)	(19,966)
Net cash provided by (used in) investing activities			43,441	(33,921)
Cash flows from financing activities:
Repayments of notes payable			(5,261)	(5,280)
Intercompany advances			(77,270)	9,788
Decrease in restricted cash				11,000
Net cash provided by (used in) financing activities			(82,531)	15,508
Effect of exchange rate changes			(1,680)	(2,269)
Increase (decrease) in cash and cash equivalents			1,144	375
Beginning of period			119	112
End of period	1,263	487	1,263	487
Combined Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net earnings (loss)	60,382	56,873	180,521	146,501
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			2,219	2,893
Depreciation and amortization			16,385	11,936
Net (gain) loss on disposition of equipment	254	7	256	7
Other			596	860
Decrease (increase) in assets:
Accounts receivable, net			(27,697)	37,034
Inventories			58,013	(87,156)
Other			(64,522)	(33,634)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(34,987)	9,112
Deferred revenue			281	(276)
Net cash provided by (used in) operating activities			131,065	87,277
Cash flows from investing activities:
Proceeds from sales of assets			10	5
Capital expenditures			(30,431)	(55,059)
Decrease (increase) in restricted cash			(1)	(1)
Net cash provided by (used in) investing activities			(30,422)	(55,055)
Cash flows from financing activities:
Proceeds from revolving notes with maturities longer than 90 days				42,563
Repayments of revolving notes with maturities longer than 90 days			(1,888)	(36,137)
Repayments of notes payable			(219)	(219)
Intercompany advances			1,981	9,209
Cash contribution to joint venture partner			(62,710)	(12,489)
Investment by joint venture partner			5,400
Other			(7)
Net cash provided by (used in) financing activities			(57,443)	2,927
Effect of exchange rate changes			(5,016)	(3,806)
Increase (decrease) in cash and cash equivalents			38,184	31,343
Beginning of period			119,276	35,057
End of period	157,460	66,400	157,460	66,400
Eliminations
Cash flows from operating activities:
Net earnings (loss)	(70,892)	(68,984)	(241,897)	(243,262)
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(9,127)
Depreciation and amortization			(77)	(71)
Net (gain) loss on disposition of equipment	$ (257)	$ (3)	(632)	(4)
Noncontrolling interest adjustments			837	20,371
Decrease (increase) in assets:
Accounts receivable, net			(59,760)	(35,807)
Inventories			9,159	1,529
Leased railcars for syndication			(7,979)	18,410
Other			62,712	10,564
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			54,046	(7,765)
Net cash provided by (used in) operating activities			(192,718)	(236,035)
Cash flows from investing activities:
Capital expenditures				398
Investment in and net advances to unconsolidated affiliates			194,245	235,637
Net cash provided by (used in) investing activities			194,245	$ 236,035
Cash flows from financing activities:
Effect of exchange rate changes			$ (1,527)