Income Taxes - Net Deferred Tax Assets (Liability) Held for Sale (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Components of Deferred Tax Assets and Liabilities [Abstract]
Net deferred tax asset (liability), long-term assets held for sale	$ 3.2	$ 1.1
Net deferred tax asset (liability), long-term liabilities held for sale	$ 6.5	$ 0.1

Deferred Tax Liabilities, Net, Long-term Liabilities Held for Sale

No definition available.

Name:	brks_DeferredTaxLiabilitiesNetLongTermLiabilitiesHeldForSale
Namespace Prefix:	brks_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant