Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Nov. 30, 2014	Nov. 30, 2013
Revenue
Revenue	$ 495,058us-gaap_Revenues	$ 490,355us-gaap_Revenues
Cost of revenue
Cost of revenue	406,990us-gaap_CostOfRevenue	428,796us-gaap_CostOfRevenue
Margin	88,068us-gaap_GrossProfit	61,559us-gaap_GrossProfit
Selling and administrative	33,729	26,109
Net gain on disposition of equipment	(83)us-gaap_GainLossOnSaleOfOtherAssets	(3,651)us-gaap_GainLossOnSaleOfOtherAssets
Restructuring charges		879us-gaap_RestructuringCharges
Earnings (loss) from operations	54,422us-gaap_OperatingIncomeLoss	38,222us-gaap_OperatingIncomeLoss
Other costs
Interest and foreign exchange	3,141gbx_InterestAndForeignExchange	4,744gbx_InterestAndForeignExchange
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	51,281	33,478
Income tax (expense) benefit	(16,054)us-gaap_IncomeTaxExpenseBenefit	(10,522)us-gaap_IncomeTaxExpenseBenefit
Earnings (loss) before earnings (loss) from unconsolidated affiliates	35,227	22,956
Earnings (loss) from unconsolidated affiliates	755	41
Net earnings (loss)	35,982us-gaap_ProfitLoss	22,997us-gaap_ProfitLoss
Net (earnings) loss attributable to noncontrolling interest	(3,196)	(7,609)
Net earnings (loss) attributable to Greenbrier	32,786us-gaap_NetIncomeLoss	15,388us-gaap_NetIncomeLoss
Manufacturing
Revenue
Revenue	379,949	359,473
Cost of revenue
Cost of revenue	316,037	311,440
Wheels & Parts
Revenue
Revenue	86,624	113,401
Cost of revenue
Cost of revenue	76,872	107,975
Leasing & Services
Revenue
Revenue	28,485	17,481
Cost of revenue
Cost of revenue	14,081	9,381
Parent
Revenue
Revenue	(122)	390
Cost of revenue
Margin	(122)	390
Selling and administrative	15,788	8,600
Earnings (loss) from operations	(15,910)	(8,210)
Other costs
Interest and foreign exchange	2,985	2,934
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	(18,895)	(11,144)
Income tax (expense) benefit	(1,210)	3,154
Earnings (loss) before earnings (loss) from unconsolidated affiliates	(20,105)	(7,990)
Earnings (loss) from unconsolidated affiliates	52,891	23,378
Net earnings (loss)	32,786	15,388
Net earnings (loss) attributable to Greenbrier	32,786	15,388
Parent \| Leasing & Services
Revenue
Revenue	(122)	390
Combined Guarantor Subsidiaries
Revenue
Revenue	390,743	317,660
Cost of revenue
Cost of revenue	328,415	286,226
Margin	62,328	31,434
Selling and administrative	7,695	9,213
Net gain on disposition of equipment	(83)	(3,174)
Restructuring charges		879
Earnings (loss) from operations	54,716	24,516
Other costs
Interest and foreign exchange	1,606	804
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	53,110	23,712
Income tax (expense) benefit	(19,993)	(9,453)
Earnings (loss) before earnings (loss) from unconsolidated affiliates	33,117	14,259
Earnings (loss) from unconsolidated affiliates	5,383	802
Net earnings (loss)	38,500	15,061
Net earnings (loss) attributable to Greenbrier	38,500	15,061
Combined Guarantor Subsidiaries \| Manufacturing
Revenue
Revenue	273,812	186,004
Cost of revenue
Cost of revenue	235,652	167,537
Combined Guarantor Subsidiaries \| Wheels & Parts
Revenue
Revenue	88,465	114,721
Cost of revenue
Cost of revenue	78,658	109,287
Combined Guarantor Subsidiaries \| Leasing & Services
Revenue
Revenue	28,466	16,935
Cost of revenue
Cost of revenue	14,105	9,402
Combined Non-Guarantor Subsidiaries
Revenue
Revenue	365,746	312,311
Cost of revenue
Cost of revenue	313,773	282,523
Margin	51,973	29,788
Selling and administrative	10,111	8,147
Net gain on disposition of equipment		(343)
Earnings (loss) from operations	41,862	21,984
Other costs
Interest and foreign exchange	(1,450)	1,006
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	43,312	20,978
Income tax (expense) benefit	(4,825)	(4,251)
Earnings (loss) before earnings (loss) from unconsolidated affiliates	38,487	16,727
Earnings (loss) from unconsolidated affiliates	47	32
Net earnings (loss)	38,534	16,759
Net (earnings) loss attributable to noncontrolling interest	(16,148)	(7,263)
Net earnings (loss) attributable to Greenbrier	22,386	9,496
Combined Non-Guarantor Subsidiaries \| Manufacturing
Revenue
Revenue	365,746	312,311
Cost of revenue
Cost of revenue	313,773	282,523
Eliminations
Revenue
Revenue	(261,309)	(140,006)
Cost of revenue
Cost of revenue	(235,198)	(139,953)
Margin	(26,111)	(53)
Selling and administrative	135	149
Net gain on disposition of equipment		(134)
Earnings (loss) from operations	(26,246)	(68)
Other costs
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	(26,246)	(68)
Income tax (expense) benefit	9,974	28
Earnings (loss) before earnings (loss) from unconsolidated affiliates	(16,272)	(40)
Earnings (loss) from unconsolidated affiliates	(57,566)	(24,171)
Net earnings (loss)	(73,838)	(24,211)
Net (earnings) loss attributable to noncontrolling interest	12,952	(346)
Net earnings (loss) attributable to Greenbrier	(60,886)	(24,557)
Eliminations \| Manufacturing
Revenue
Revenue	(259,609)	(138,842)
Cost of revenue
Cost of revenue	(233,388)	(138,620)
Eliminations \| Wheels & Parts
Revenue
Revenue	(1,841)	(1,320)
Cost of revenue
Cost of revenue	(1,786)	(1,312)
Eliminations \| Leasing & Services
Revenue
Revenue	141	156
Cost of revenue
Cost of revenue	$ (24)	$ (21)

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