Revenue from Contracts with Customers - Segment Information (Details) - segment	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Number of reportable segments	2	2	2	2
Number of reporting units	6	6	6	6
Brooks Semiconductor Solutions Group
Segment Reporting Information [Line Items]
Number of reporting units	3	3	3	3
Brooks Life Sciences
Segment Reporting Information [Line Items]
Number of reporting units	3	3	3	3