Acquisitions - Pro Forma Information - Additional Information (Details) - GENEWIZ - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Business Acquisition, Pro Forma Information [Abstract]
Depreciation	$ 1.6	$ 12.7
One-time nonrecurring compensation and transaction costs	0.0	53.6
Interest expense	$ 2.0	$ 19.8

The pro forma one-time nonrecurring compensation expenses and transaction costs for the period as if the business combination or combinations had been completed at the beginning of a period.

No definition available.

Name:	brks_BusinessAcquisitionProFormaOneTimeNonrecurringCompensationExpenseAndTransactionCosts
Namespace Prefix:	brks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration