Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Jan. 04, 2020	Dec. 29, 2018	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 153,217	$ 154,926
Diesel buses
Disaggregation of Revenue [Line Items]
Net sales	76,750	89,820
Alternative fuel buses
Disaggregation of Revenue [Line Items]
Net sales	51,734	43,081
Other
Disaggregation of Revenue [Line Items]
Net sales	6,843	6,802
Parts
Disaggregation of Revenue [Line Items]
Net sales	$ 17,890	$ 15,223
Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Adoption of new revenue recognition standard (ASC 606) adjustment			$ (714)