Document and Entity Information - shares	3 Months Ended
	Jan. 04, 2020	Feb. 07, 2020
Document and Entity Information [Abstract]
Entity Registrant Name	Blue Bird Corp
Entity Central Index Key	0001589526
Current Fiscal Year End Date	--10-03
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jan. 04, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		26,839,825
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Current Reporting Status	Yes