Condensed Consolidating Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014
Revenue
Revenue	$ 630,149us-gaap_Revenues	$ 502,216us-gaap_Revenues	$ 1,125,207us-gaap_Revenues	$ 992,571us-gaap_Revenues
Cost of revenue
Cost of revenue	504,839us-gaap_CostOfRevenue	444,365us-gaap_CostOfRevenue	911,829us-gaap_CostOfRevenue	873,161us-gaap_CostOfRevenue
Margin	125,310us-gaap_GrossProfit	57,851us-gaap_GrossProfit	213,378us-gaap_GrossProfit	119,410us-gaap_GrossProfit
Selling and administrative	32,899	28,125	66,628	54,234
Net gain on disposition of equipment	(121)us-gaap_GainLossOnSaleOfOtherAssets	(5,416)us-gaap_GainLossOnSaleOfOtherAssets	(204)us-gaap_GainLossOnSaleOfOtherAssets	(9,067)us-gaap_GainLossOnSaleOfOtherAssets
Restructuring charges		540us-gaap_RestructuringCharges		1,419us-gaap_RestructuringCharges
Earnings (loss) from operations	92,532us-gaap_OperatingIncomeLoss	34,602us-gaap_OperatingIncomeLoss	146,954us-gaap_OperatingIncomeLoss	72,824us-gaap_OperatingIncomeLoss
Other costs
Interest and foreign exchange	1,929gbx_InterestAndForeignExchange	4,099gbx_InterestAndForeignExchange	5,070gbx_InterestAndForeignExchange	8,843gbx_InterestAndForeignExchange
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	90,603	30,503	141,884	63,981
Income tax (expense) benefit	(29,372)us-gaap_IncomeTaxExpenseBenefit	(9,883)us-gaap_IncomeTaxExpenseBenefit	(45,426)us-gaap_IncomeTaxExpenseBenefit	(20,405)us-gaap_IncomeTaxExpenseBenefit
Earnings (loss) before earnings (loss) from unconsolidated affiliates	61,231	20,620	96,458	43,576
Earnings (loss) from unconsolidated affiliates	(185)	(67)	570	(26)
Net earnings (loss)	61,046us-gaap_ProfitLoss	20,553us-gaap_ProfitLoss	97,028us-gaap_ProfitLoss	43,550us-gaap_ProfitLoss
Net (earnings) loss attributable to noncontrolling interest	(10,695)	(4,966)	(13,891)	(12,575)
Net earnings (loss) attributable to Greenbrier	50,351us-gaap_NetIncomeLoss	15,587us-gaap_NetIncomeLoss	83,137us-gaap_NetIncomeLoss	30,975us-gaap_NetIncomeLoss
Manufacturing
Revenue
Revenue	505,241	347,755	885,190	707,228
Cost of revenue
Cost of revenue	403,227	306,572	719,264	618,012
Wheels & Parts
Revenue
Revenue	102,640	136,540	189,264	249,941
Cost of revenue
Cost of revenue	92,768	127,940	169,640	235,915
Leasing & Services
Revenue
Revenue	22,268	17,921	50,753	35,402
Cost of revenue
Cost of revenue	8,844	9,853	22,925	19,234
Parent
Revenue
Revenue	295	367	173	757
Cost of revenue
Margin	295	367	173	757
Selling and administrative	14,477	9,111	30,265	17,711
Earnings (loss) from operations	(14,182)	(8,744)	(30,092)	(16,954)
Other costs
Interest and foreign exchange	3,120	2,899	6,105	5,833
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	(17,302)	(11,643)	(36,197)	(22,787)
Income tax (expense) benefit	(7,481)	4,281	(8,691)	7,435
Earnings (loss) before earnings (loss) from unconsolidated affiliates	(24,783)	(7,362)	(44,888)	(15,352)
Earnings (loss) from unconsolidated affiliates	75,134	22,949	128,025	46,327
Net earnings (loss)	50,351	15,587	83,137	30,975
Net earnings (loss) attributable to Greenbrier	50,351	15,587	83,137	30,975
Parent \| Leasing & Services
Revenue
Revenue	295	367	173	757
Combined Guarantor Subsidiaries
Revenue
Revenue	448,207	374,781	838,950	692,441
Cost of revenue
Cost of revenue	372,453	339,908	700,868	626,134
Margin	75,754	34,873	138,082	66,307
Selling and administrative	8,522	9,944	16,217	19,157
Net gain on disposition of equipment	(120)	(4,971)	(203)	(8,145)
Restructuring charges		540		1,419
Earnings (loss) from operations	67,352	29,360	122,068	53,876
Other costs
Interest and foreign exchange	1,743	959	3,349	1,763
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	65,609	28,401	118,719	52,113
Income tax (expense) benefit	(16,420)	(10,100)	(36,413)	(19,553)
Earnings (loss) before earnings (loss) from unconsolidated affiliates	49,189	18,301	82,306	32,560
Earnings (loss) from unconsolidated affiliates	10,852	1,643	16,235	2,445
Net earnings (loss)	60,041	19,944	98,541	35,005
Net earnings (loss) attributable to Greenbrier	60,041	19,944	98,541	35,005
Combined Guarantor Subsidiaries \| Manufacturing
Revenue
Revenue	322,665	219,195	596,477	405,199
Cost of revenue
Cost of revenue	269,619	200,464	505,271	368,001
Combined Guarantor Subsidiaries \| Wheels & Parts
Revenue
Revenue	103,706	138,191	192,171	252,912
Cost of revenue
Cost of revenue	93,966	129,570	172,624	238,857
Combined Guarantor Subsidiaries \| Leasing & Services
Revenue
Revenue	21,836	17,395	50,302	34,330
Cost of revenue
Cost of revenue	8,868	9,874	22,973	19,276
Combined Non-Guarantor Subsidiaries
Revenue
Revenue	427,556	305,329	793,302	617,640
Cost of revenue
Cost of revenue	359,452	278,474	673,225	560,997
Margin	68,104	26,855	120,077	56,643
Selling and administrative	10,146	8,920	20,257	17,067
Net gain on disposition of equipment		(272)		(615)
Earnings (loss) from operations	57,958	18,207	99,820	40,191
Other costs
Interest and foreign exchange	(2,934)	241	(4,384)	1,247
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	60,892	17,966	104,204	38,944
Income tax (expense) benefit	(9,846)	(5,405)	(14,671)	(9,656)
Earnings (loss) before earnings (loss) from unconsolidated affiliates	51,046	12,561	89,533	29,288
Earnings (loss) from unconsolidated affiliates	48	45	95	77
Net earnings (loss)	51,094	12,606	89,628	29,365
Net (earnings) loss attributable to noncontrolling interest	(19,429)	(7,269)	(35,577)	(14,532)
Net earnings (loss) attributable to Greenbrier	31,665	5,337	54,051	14,833
Combined Non-Guarantor Subsidiaries \| Manufacturing
Revenue
Revenue	427,555	305,328	793,301	617,639
Cost of revenue
Cost of revenue	359,452	278,474	673,225	560,997
Combined Non-Guarantor Subsidiaries \| Leasing & Services
Revenue
Revenue	1	1	1	1
Eliminations
Revenue
Revenue	(245,909)	(178,261)	(507,218)	(318,267)
Cost of revenue
Cost of revenue	(227,066)	(174,017)	(462,264)	(313,970)
Margin	(18,843)	(4,244)	(44,954)	(4,297)
Selling and administrative	(246)	150	(111)	299
Net gain on disposition of equipment	(1)	(173)	(1)	(307)
Earnings (loss) from operations	(18,596)	(4,221)	(44,842)	(4,289)
Other costs
Earnings (loss) before income taxes and earnings (loss) from unconsolidated affiliates	(18,596)	(4,221)	(44,842)	(4,289)
Income tax (expense) benefit	4,375	1,341	14,349	1,369
Earnings (loss) before earnings (loss) from unconsolidated affiliates	(14,221)	(2,880)	(30,493)	(2,920)
Earnings (loss) from unconsolidated affiliates	(86,219)	(24,704)	(143,785)	(48,875)
Net earnings (loss)	(100,440)	(27,584)	(174,278)	(51,795)
Net (earnings) loss attributable to noncontrolling interest	8,734	2,303	21,686	1,957
Net earnings (loss) attributable to Greenbrier	(91,706)	(25,281)	(152,592)	(49,838)
Eliminations \| Manufacturing
Revenue
Revenue	(244,979)	(176,768)	(504,588)	(315,610)
Cost of revenue
Cost of revenue	(225,844)	(172,366)	(459,232)	(310,986)
Eliminations \| Wheels & Parts
Revenue
Revenue	(1,066)	(1,651)	(2,907)	(2,971)
Cost of revenue
Cost of revenue	(1,198)	(1,630)	(2,984)	(2,942)
Eliminations \| Leasing & Services
Revenue
Revenue	136	158	277	314
Cost of revenue
Cost of revenue	$ (24)	$ (21)	$ (48)	$ (42)

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