Document and Entity Information - shares	9 Months Ended
	Jul. 04, 2020	Aug. 07, 2020
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jul. 04, 2020
Document Transition Report	false
Entity File Number	001-36267
Entity Registrant Name	BLUE BIRD CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-3891989
Entity Address, Address Line One	3920 Arkwright Road
Entity Address, Address Line Two	2nd Floor
Entity Address, City or Town	Macon
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	31210
City Area Code	478
Local Phone Number	822-2801
Title of 12(b) Security	Common stock, $0.0001 par value
Trading Symbol	BLBD
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		27,048,404
Entity Central Index Key	0001589526
Current Fiscal Year End Date	--10-03
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false