Goodwill and Intangible Assets - Goodwill Roll Forward (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	$ 501,536
Acquisitions and adjustments	11,557
Goodwill, net of accumulated impairments, ending balance	513,093
Brooks Semiconductor Solutions Group
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	48,359
Acquisitions and adjustments	(129)
Goodwill, net of accumulated impairments, ending balance	48,230
Brooks Life Sciences Products
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	103,278
Acquisitions and adjustments	2,573
Goodwill, net of accumulated impairments, ending balance	105,851
Brooks Life Sciences Services
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	349,899
Acquisitions and adjustments	9,113
Goodwill, net of accumulated impairments, ending balance	$ 359,012