Goodwill and Intangible Assets - Goodwill Roll Forward (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	$ 501,536
Acquisitions and adjustments	49,790
Goodwill, net of accumulated impairments, ending balance	551,326
Brooks Semiconductor Solutions Group
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	48,359
Acquisitions and adjustments	32,911
Goodwill, net of accumulated impairments, ending balance	81,270
Brooks Life Sciences Products
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	103,278
Acquisitions and adjustments	7,493
Goodwill, net of accumulated impairments, ending balance	110,771
Brooks Life Sciences Services
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	349,899
Acquisitions and adjustments	9,386
Goodwill, net of accumulated impairments, ending balance	$ 359,285