Acquisitions and discontinued operations - Acquisitions (Details)	3 Months Ended
Dec. 28, 2019 USD ($)
Acquisitions and discontinued operations
Number of Businesses Acquired	2

The number of businesses acquired by the entity during the period.

No definition available.

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration