Nature of Business and Basis of Presentation	6 Months Ended
Nature of Business and Basis of Presentation	Apr. 01, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Nature of Business Blue Bird Body Company ("BBBC"), a wholly-owned subsidiary of Blue Bird Corporation, was incorporated in 1958 and has manufactured, assembled and sold school buses to a variety of municipal, federal and commercial customers since 1927. The majority of BBBC’s sales are made to an independent dealer network, which in turn sells buses to ultimate end users. References in these notes to condensed consolidated financial statements to “Blue Bird,” the “Company,” “we,” “our,” or “us” relate to Blue Bird Corporation and its wholly-owned subsidiaries, unless the context specifically indicates otherwise. We are headquartered in Macon, Georgia. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant inter-company transactions and accounts have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial reporting and Article 8 of Regulation S-X. The Company’s fiscal year ends on the Saturday closest to September 30 with its quarters consisting of thirteen weeks in most years. The fiscal years ending September 30, 2023 ("fiscal 2023") and ended October 1, 2022 ("fiscal 2022") consist or consisted of 52 weeks. The second quarters of fiscal 2023 and fiscal 2022 both included 13 weeks. The six month periods in fiscal 2023 and 2022 both included 26 weeks. In the opinion of management, all adjustments considered necessary for a fair presentation of financial results have been made. Such adjustments consist of only those of a normal recurring nature. Operating results for any interim period are not necessarily indicative of the results that may be expected for the entire year. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet data as of October 1, 2022 was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. For additional information, including the Company’s significant accounting policies, refer to the consolidated financial statements and related footnotes as of and for the fiscal year ended October 1, 2022 as set forth in the Company's fiscal 2022 Form 10-K filed with the Securities and Exchange Commission ("SEC") on December 12, 2022. Impacts of COVID-19 and Subsequent Supply Chain Constraints on our Business Towards the end of our second quarter of the fiscal year that ended October 3, 2020 ("fiscal 2020"), the novel coronavirus known as "COVID-19" spread throughout the world, resulting in a global pandemic. Countermeasures taken to address the COVID-19 pandemic included virtual and hybrid schooling in many jurisdictions throughout the United States of America ("U.S.") and Canada. The uncertainty of when and how schools would open materially affected demand for new buses and replacement/maintenance parts during the second half of fiscal 2020 and first half of the fiscal year that ended October 2, 2021 ("fiscal 2021"), significantly impacting our business and operations. Demand for school buses strengthened substantially during the second half of fiscal 2021 as COVID-19 vaccines were administered and many jurisdictions began preparing for a return to in-person learning environments for the new school year that began in mid-August to early September 2021. However, during this same period of time, the Company, and automotive industry as a whole, began experiencing significant supply chain constraints resulting from, among others, labor shortages; the lack of maintenance on, and acquisition of, capital assets by suppliers during the extended COVID-19 global lockdowns; significant increased demand for consumer products containing certain materials required for the production of vehicles, such as microchips, as consumers spent stimulus and other funds on items for their homes; etc. These supply chain disruptions had a significant adverse impact on our operations and results during the second half of fiscal 2021 and all of fiscal 2022 due to higher purchasing costs, including freight costs incurred to expedite receipt of critical components, increased manufacturing inefficiencies and our inability to complete the production of buses to fulfill sales orders. Towards the end of fiscal 2022 and continuing into fiscal 2023, there were slight improvements in the supply chain's ability to deliver the parts and components necessary to support our production operations, resulting in increased (i) manufacturing efficiencies and (ii) production of buses to fulfill sales orders during the first half of fiscal 2023. However, the higher costs charged by suppliers to procure inventory continued into the first half of fiscal 2023 and had a significant adverse impact on our operations and results. Specifically, such cost increases outpaced the increases in sales prices that we charged for the buses that were sold during the first quarter of fiscal 2023, many of which were included in the backlog of fixed price sales orders originating in fiscal 2021 and the early months of fiscal 2022 that carried forward into fiscal 2023. During the second quarter of fiscal 2023, the buses that were sold were generally included in the backlog of fixed price sales orders originating more recently (i.e., the latter months of fiscal 2022 and in fiscal 2023), with the cumulative increases in sales prices we charged for those buses generally outpacing the higher costs we paid to procure inventory, resulting in gross profit during the quarter. However, the gross margin on bus sales during the second quarter of fiscal 2023 still lags the historical gross margin reported prior to the COVID-19 pandemic. Additionally, Russian military forces launched a large-scale invasion of Ukraine on February 24, 2022, which further exacerbated global supply chain disruptions. While the Company has no assets or customers in either of these countries, this military conflict significantly impacted our financial results during the second half of fiscal 2022 and continuing into the first half of fiscal 2023, primarily in an indirect manner since the Company does not sell to customers located in, or source goods directly from, either country. Specifically, it has contributed to increased a) costs charged by suppliers for the purchase of inventory that is at least partially dependent on resources originating from either of the countries and b) freight costs, both of which negatively impacted the gross profit recognized on sales during the second half of fiscal 2022 and continuing into the first half of fiscal 2023. Significant uncertainty exists concerning the magnitude and duration of the the pandemic and subsequent supply chain constraints and accordingly, precludes any prediction as to the ultimate severity of the adverse impacts on our business, financial condition, results of operations, and liquidity. Use of Estimates and Assumptions The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions. At the date of the financial statements, these estimates and assumptions affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities, and during the reporting period, these estimates and assumptions affect the reported amounts of revenues and expenses. For example, significant management judgments are required in determining excess, obsolete, or unsalable inventory; the allowance for doubtful accounts; potential impairment of long-lived assets, goodwill and intangible assets; and the accounting for self-insurance reserves, warranty reserves, pension obligations, income taxes, environmental liabilities and contingencies. Future events, including the extent and duration of any COVID-19 outbreaks and continued supply chain constraints and their related economic impacts, and their effects cannot be predicted with certainty, and, accordingly, the Company’s accounting estimates require the exercise of judgment. The accounting estimates used in the preparation of the Company’s condensed consolidated financial statements may change as new events occur, as more experience is acquired, as additional information is obtained and as the Company’s operating environment changes. The Company evaluates and updates its assumptions and estimates on an ongoing basis and may employ outside experts to assist in the Company’s evaluations. Actual results could differ from the estimates that the Company has used.