Commitments and Contingencies	12 Months Ended
Aug. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 22 — Commitments and Contingencies Portland Harbor Superfund Site The Company’s former Portland, Oregon manufacturing facility (the Portland Property) is located adjacent to the Willamette River. In December 2000, the U.S. Environmental Protection Agency (EPA) classified portions of the Willamette River bed known as the Portland Harbor, including the portion fronting the Company’s manufacturing facility, as a federal "National Priority List" or "Superfund" site due to sediment contamination (the Portland Harbor Site). The Company and more than 140 other parties have received a "General Notice" of potential liability from the EPA relating to the Portland Harbor Site. The letter advised the Company that it may be liable for the costs of investigation and remediation (which liability may be joint and several with other potentially responsible parties) as well as for natural resource damages resulting from releases of hazardous substances to the site. Ten private and public entities, including the Company (the Lower Willamette Group or LWG), signed an Administrative Order on Consent (AOC) to perform a remedial investigation/feasibility study (RI/FS) of the Portland Harbor Site under EPA oversight, and several additional entities did not sign such consent, but nevertheless contributed financially to the effort. The EPA-mandated RI/FS was produced by the LWG and cost over $110 million during a 17-year period. The Company bore a percentage of the total costs incurred by the LWG in connection with the investigation. The Company’s aggregate expenditure during the 17-year period was not material. Some or all of any such outlay may be recoverable from other responsible parties. The EPA issued its Record of Decision (ROD) for the Portland Harbor Site on January 6, 2017 and accordingly on October 26, 2017, the AOC was terminated. Separate from the process described above, which focused on the type of remediation to be performed at the Portland Harbor Site and the schedule for such remediation, 96 parties, including the State of Oregon and the federal government, are participating in a non-judicial, mediated allocation process to try to allocate costs associated with remediation of the Portland Harbor Site. The Company will continue to participate in the allocation process. Approximately 110 additional parties signed tolling agreements related to such allocations. On April 23, 2009, the Company and the other AOC signatories filed suit against 69 other parties due to a possible limitations period for some such claims; Arkema Inc. et al v. A & C Foundry Products, Inc. et al, U.S. District Court, District of Oregon, Case #3:09-cv-453-PK. All but 12 of these parties elected to sign tolling agreements and be dismissed without prejudice, and the case has been stayed by the court until January 14, 2025. The EPA's January 6, 2017 ROD identifies a clean-up remedy that the EPA estimates will take 13 years of active remediation, followed by 30 years of monitoring with an estimated undiscounted cost of $1.7 billion. The EPA typically expects its cost estimates to be accurate within a range of -30% to +50%, but this ROD states that changes in costs are likely to occur. The EPA has identified several Sediment Decision Units within the ROD cleanup area. One of the units, RM9W, includes the nearshore area of the river sediments offshore of the Portland Property as well as downstream of the facility. It also includes a portion of the Portland Property's riverbank. The ROD does not break down total remediation costs by Sediment Decision Unit. The EPA requested that potentially responsible parties enter AOCs during 2019 agreeing to conduct remedial design studies. Some parties have signed AOCs, including one party with respect to RM9W which includes the area offshore of the Portland Property. The Company has not signed an AOC in connection with remedial design, but is assisting in funding a portion of the RM9W remedial design. The ROD does not address responsibility for the costs of clean-up, nor does it allocate such costs among the potentially responsible parties. Responsibility for funding and implementing the EPA's selected cleanup remedy will be determined at an unspecified later date. Based on the investigation to date, the Company believes that it did not contribute in any material way to contaminants of concern in the river sediments or the damage of natural resources in the Portland Harbor Site and that the damage in the area of the Portland Harbor Site adjacent to the Portland Property precedes the Company’s ownership of the Portland Property. Because these environmental investigations are still underway, sufficient information is currently not available to determine the Company’s liability, if any, for the cost of any required remediation or restoration of the Portland Harbor Site or to estimate a range of potential loss. Based on the results of the pending investigations and future assessments of natural resource damages, the Company may be required to incur costs associated with additional phases of investigation or remedial action, and may be liable for damages to natural resources. On January 30, 2017 the Confederated Tribes and Bands of Yakama Nation sued 33 parties including the Company as well as the federal government and the State of Oregon for costs it incurred in assessing alleged natural resource damages to the Columbia River from contaminants deposited in Portland Harbor. Confederated Tribes and Bands of the Yakama Nation v. Air Liquide America Corp., et al., U.S. Court for the District of Oregon Case No. 3i17-CV-00164-SB. The complaint does not specify the amount of damages the plaintiff will seek. The case has been stayed until January 14, 2025. Oregon Department of Environmental Quality (DEQ) Regulation of Portland Property The Company entered into a Voluntary Cleanup Agreement with the Oregon Department of Environmental Quality (DEQ) in which the Company agreed to conduct an investigation of whether, and to what extent, past or present operations at the Portland Property may have released hazardous substances into the environment. The Company has also signed an Order on Consent with the DEQ to finalize the investigation of potential onsite sources of contamination that may have a release pathway to the Willamette River. The Company’s aggregate expenditure has not been material, however it could incur significant expenses for remediation. Some or all of any such outlay may be recoverable from other responsible parties. Sale of Portland Property The Company sold the Portland Property in May 2023, but remains potentially liable with respect to the above matters. Any of these matters could adversely affect the Company's business and Consolidated Financial Statements. However, any contamination or exacerbation of contamination that occurs after the sale of the property will be the liability of the current and future owners and operators of the Portland Property. Other Litigation, Commitments and Contingencies From time to time, Greenbrier is involved as a defendant in litigation in the ordinary course of business, the outcomes of which cannot be predicted with certainty. While the ultimate outcome of such legal proceedings cannot be determined at this time, the Company believes that the resolution of pending litigation will not have a material adverse effect on the Company's Consolidated Financial Statements. As of August 31, 2023, the Company had outstanding letters of credit aggregating to $4.9 million associated with performance guarantees, facility leases and workers compensation insurance.

Commitments and Contingencies

12 Months Ended

Aug. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Note 22 — Commitments and Contingencies

Portland Harbor Superfund Site

The Company’s former Portland, Oregon manufacturing facility (the Portland Property) is located adjacent to the Willamette River. In December 2000, the U.S. Environmental Protection Agency (EPA) classified portions of the Willamette River bed known as the Portland Harbor, including the portion fronting the Company’s manufacturing facility, as a federal "National Priority List" or "Superfund" site due to sediment contamination (the Portland Harbor Site). The Company and more than 140 other parties have received a "General Notice" of potential liability from the EPA relating to the Portland Harbor Site. The letter advised the Company that it may be liable for the costs of investigation and remediation (which liability may be joint and several with other potentially responsible parties) as well as for natural resource damages resulting from releases of hazardous substances to the site. Ten private and public entities, including the Company (the Lower Willamette Group or LWG), signed an Administrative Order on Consent (AOC) to perform a remedial investigation/feasibility study (RI/FS) of the Portland Harbor Site under EPA oversight, and several additional entities did not sign such consent, but nevertheless contributed financially to the effort. The EPA-mandated RI/FS was produced by the LWG and cost over $110 million during a 17-year period. The Company bore a percentage of the total costs incurred by the LWG in connection with the investigation. The Company’s aggregate expenditure during the 17-year period was not material. Some or all of any such outlay may be recoverable from other responsible parties. The EPA issued its Record of Decision (ROD) for the Portland Harbor Site on January 6, 2017 and accordingly on October 26, 2017, the AOC was terminated.

Separate from the process described above, which focused on the type of remediation to be performed at the Portland Harbor Site and the schedule for such remediation, 96 parties, including the State of Oregon and the federal government, are participating in a non-judicial, mediated allocation process to try to allocate costs associated with remediation of the Portland Harbor Site. The Company will continue to participate in the allocation process. Approximately 110 additional parties signed tolling agreements related to such allocations. On April 23, 2009, the Company and the other AOC signatories filed suit against 69 other parties due to a possible limitations period for some such claims; Arkema Inc. et al v. A & C Foundry Products, Inc. et al, U.S. District Court, District of Oregon, Case #3:09-cv-453-PK. All but 12 of these parties elected to sign tolling agreements and be dismissed without prejudice, and the case has been stayed by the court until January 14, 2025.

The EPA's January 6, 2017 ROD identifies a clean-up remedy that the EPA estimates will take 13 years of active remediation, followed by 30 years of monitoring with an estimated undiscounted cost of $1.7 billion. The EPA typically expects its cost estimates to be accurate within a range of -30% to +50%, but this ROD states that changes in costs are likely to occur. The EPA has identified several Sediment Decision Units within the ROD cleanup area. One of the units, RM9W, includes the nearshore area of the river sediments offshore of the Portland Property as well as downstream of the facility. It also includes a portion of the Portland Property's riverbank. The ROD does not break down total remediation costs by Sediment Decision Unit. The EPA requested that potentially responsible parties enter AOCs during 2019 agreeing to conduct remedial design studies. Some parties have signed AOCs, including one party with respect to RM9W which includes the area offshore of the Portland Property. The Company has not signed an AOC in connection with remedial design, but is assisting in funding a portion of the RM9W remedial design.

The ROD does not address responsibility for the costs of clean-up, nor does it allocate such costs among the potentially responsible parties. Responsibility for funding and implementing the EPA's selected cleanup remedy will be determined at an unspecified later date. Based on the investigation to date, the Company believes that it did not contribute in any material way to contaminants of concern in the river sediments or the damage of natural resources in the Portland Harbor Site and that the damage in the area of the Portland Harbor Site adjacent to the Portland Property precedes the Company’s ownership of the Portland Property. Because these environmental investigations are still underway, sufficient information is currently not available to determine the Company’s liability, if any, for the cost of any required remediation or restoration of the Portland Harbor Site or to estimate a range of potential loss. Based on the results of the pending investigations and future assessments of natural resource damages, the Company may be required to incur costs associated with additional phases of investigation or remedial action, and may be liable for damages to natural resources.

On January 30, 2017 the Confederated Tribes and Bands of Yakama Nation sued 33 parties including the Company as well as the federal government and the State of Oregon for costs it incurred in assessing alleged natural resource damages to the Columbia River from contaminants deposited in Portland Harbor. Confederated Tribes and Bands of the Yakama Nation v. Air Liquide America Corp., et al., U.S. Court for the District of Oregon Case No. 3i17-CV-00164-SB. The complaint does not specify the amount of damages the plaintiff will seek. The case has been stayed until January 14, 2025.

Oregon Department of Environmental Quality (DEQ) Regulation of Portland Property

The Company entered into a Voluntary Cleanup Agreement with the Oregon Department of Environmental Quality (DEQ) in which the Company agreed to conduct an investigation of whether, and to what extent, past or present operations at the Portland Property may have released hazardous substances into the environment. The Company has also signed an Order on Consent with the DEQ to finalize the investigation of potential onsite sources of contamination that may have a release pathway to the Willamette River. The Company’s aggregate expenditure has not been material, however it could incur significant expenses for remediation. Some or all of any such outlay may be recoverable from other responsible parties.

Sale of Portland Property

The Company sold the Portland Property in May 2023, but remains potentially liable with respect to the above matters. Any of these matters could adversely affect the Company's business and Consolidated Financial Statements. However, any contamination or exacerbation of contamination that occurs after the sale of the property will be the liability of the current and future owners and operators of the Portland Property.

Other Litigation, Commitments and Contingencies

From time to time, Greenbrier is involved as a defendant in litigation in the ordinary course of business, the outcomes of which cannot be predicted with certainty. While the ultimate outcome of such legal proceedings cannot be determined at this time, the Company believes that the resolution of pending litigation will not have a material adverse effect on the Company's Consolidated Financial Statements.

As of August 31, 2023, the Company had outstanding letters of credit aggregating to $4.9 million associated with performance guarantees, facility leases and workers compensation insurance.