Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2015	May. 31, 2014
Cash flows from operating activities:
Net earnings (loss)	$ 70,325	$ 46,096	$ 167,353	$ 89,646
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(5,245)	(6,745)
Depreciation and amortization			33,258	30,824
Net (gain) loss on disposition of equipment	(720)	(5,619)	(924)	(14,686)
Stock based compensation expense			13,176	6,454
Noncontrolling interest adjustments			20,371	2,953
Other			1,008	388
Decrease (increase) in assets:
Accounts receivable			(8,769)	(26,226)
Inventories			(124,906)	(21,722)
Leased railcars for syndication			(90,914)	(25,420)
Other			(1,666)	(2,491)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			23,135	36,507
Deferred revenue			3,680	12,258
Net cash provided by (used in) operating activities			29,557	81,740
Cash flows from investing activities:
Proceeds from sales of assets			4,628	39,515
Capital expenditures			(75,892)	(34,522)
Decrease (increase) in restricted cash			228	(661)
Investment in and net advances to unconsolidated affiliates			(29,923)	(1,253)
Other			715
Net cash provided by (used in) investing Activities			(100,244)	3,079
Cash flows from financing activities:
Net changes in revolving notes with maturities of 90 days or less			73,000
Proceeds from revolving notes with maturities longer than 90 days			42,563	34,674
Repayment of revolving notes with maturities longer than 90 days			(36,137)	(64,801)
Repayments of notes payable			(5,504)	(126,821)
Proceeds from notes payable				200,000
Debt issuance costs				(382)
Repurchase of stock			(48,451)	(26,293)
Dividends			(12,069)
Decrease in restricted cash			11,000
Cash distribution to joint venture partner			(12,489)	(3,109)
Investment by joint venture partner				419
Excess tax benefit from restricted stock awards			2,964	109
Other			(248)
Net cash provided by (used in) financing activities			14,629	13,796
Effect of exchange rate changes			(6,075)	2,442
Increase (decrease) in cash and cash equivalents			(62,133)	101,057
Beginning of period			184,916	97,435
End of period	122,783	198,492	122,783	198,492
Parent
Cash flows from operating activities:
Net earnings (loss)	42,811	33,588	125,948	64,563
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(138)	(4,194)
Depreciation and amortization			1,484	1,427
Stock based compensation expense			13,176	6,454
Other			43
Decrease (increase) in assets:
Accounts receivable			50	36,573
Other			20,641	(1,220)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(3,824)	(22,404)
Deferred revenue			(122)	(116)
Net cash provided by (used in) operating activities			157,258	81,083
Cash flows from investing activities:
Capital expenditures			(2,424)	(3,543)
Investment in and net advances to unconsolidated affiliates			(245,594)	(91,939)
Other			715
Net cash provided by (used in) investing Activities			(247,303)	(95,482)
Cash flows from financing activities:
Net changes in revolving notes with maturities of 90 days or less			73,000
Repayments of notes payable			(5)
Intercompany advances			(18,997)	137,633
Repurchase of stock			(48,451)	(26,293)
Dividends			(12,069)
Excess tax benefit from restricted stock awards			2,964	109
Other			(248)
Net cash provided by (used in) financing activities			(3,806)	111,449
Increase (decrease) in cash and cash equivalents			(93,851)	97,050
Beginning of period			149,747	63,173
End of period	55,896	160,223	55,896	160,223
Combined Guarantor Subsidiaries
Cash flows from operating activities:
Net earnings (loss)	39,625	37,001	138,166	72,006
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			(8,000)	(1,789)
Depreciation and amortization			19,909	20,713
Net (gain) loss on disposition of equipment	(724)	(5,411)	(927)	(13,556)
Other			105	372
Decrease (increase) in assets:
Accounts receivable			(10,046)	(43,867)
Inventories			(39,279)	20,456
Leased railcars for syndication			(109,324)	(28,371)
Other			763	81
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			25,612	9,143
Deferred revenue			4,078	10,798
Net cash provided by (used in) operating activities			21,057	45,986
Cash flows from investing activities:
Proceeds from sales of assets			4,623	38,509
Capital expenditures			(18,807)	(9,929)
Decrease (increase) in restricted cash			229	(660)
Investment in and net advances to unconsolidated affiliates			(19,966)	(7,710)
Net cash provided by (used in) investing Activities			(33,921)	20,210
Cash flows from financing activities:
Repayments of notes payable			(5,280)	(126,400)
Intercompany advances			9,788	(139,741)
Proceeds from notes payable				200,000
Debt issuance costs				(382)
Decrease in restricted cash			11,000
Net cash provided by (used in) financing activities			15,508	(66,523)
Effect of exchange rate changes			(2,269)	362
Increase (decrease) in cash and cash equivalents			375	35
Beginning of period			112	25
End of period	487	60	487	60
Combined Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net earnings (loss)	56,873	28,746	146,501	58,111
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Deferred income taxes			2,893	(762)
Depreciation and amortization			11,936	8,746
Net (gain) loss on disposition of equipment	7	(205)	7	(820)
Other			860	16
Decrease (increase) in assets:
Accounts receivable			37,034	694
Inventories			(87,156)	(42,225)
Other			(33,634)	(2,788)
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			9,112	31,774
Deferred revenue			(276)	1,574
Net cash provided by (used in) operating activities			87,277	54,320
Cash flows from investing activities:
Proceeds from sales of assets			5	1,006
Capital expenditures			(55,059)	(21,050)
Decrease (increase) in restricted cash			(1)	(1)
Investment in and net advances to unconsolidated affiliates				(1,253)
Net cash provided by (used in) investing Activities			(55,055)	(21,298)
Cash flows from financing activities:
Proceeds from revolving notes with maturities longer than 90 days			42,563	34,674
Repayment of revolving notes with maturities longer than 90 days			(36,137)	(64,801)
Repayments of notes payable			(219)	(421)
Intercompany advances			9,209	2,108
Cash distribution to joint venture partner			(12,489)	(3,109)
Investment by joint venture partner				419
Net cash provided by (used in) financing activities			2,927	(31,130)
Effect of exchange rate changes			(3,806)	2,080
Increase (decrease) in cash and cash equivalents			31,343	3,972
Beginning of period			35,057	34,237
End of period	66,400	38,209	66,400	38,209
Eliminations
Cash flows from operating activities:
Net earnings (loss)	(68,984)	(53,239)	(243,262)	(105,034)
Adjustments to reconcile net earnings (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization			(71)	(62)
Net (gain) loss on disposition of equipment	$ (3)	$ (3)	(4)	(310)
Noncontrolling interest adjustments			20,371	2,953
Decrease (increase) in assets:
Accounts receivable			(35,807)	(19,626)
Inventories			1,529	47
Leased railcars for syndication			18,410	2,951
Other			10,564	1,436
Increase (decrease) in liabilities:
Accounts payable and accrued liabilities			(7,765)	17,994
Deferred revenue				2
Net cash provided by (used in) operating activities			(236,035)	(99,649)
Cash flows from investing activities:
Capital expenditures			398
Investment in and net advances to unconsolidated affiliates			235,637	99,649
Net cash provided by (used in) investing Activities			$ 236,035	$ 99,649