Goodwill and Intangible Assets - Goodwill Roll Forward (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2020 USD ($)
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	$ 501,536
Acquisitions and adjustments	11,453
Goodwill, net of accumulated impairments, ending balance	512,989
Brooks Semiconductor Solutions Group
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	48,359
Acquisitions and adjustments	354
Goodwill, net of accumulated impairments, ending balance	48,713
Brooks Life Sciences Products
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	103,278
Acquisitions and adjustments	2,059
Goodwill, net of accumulated impairments, ending balance	105,337
Brooks Life Sciences Services
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	349,899
Acquisitions and adjustments	9,040
Goodwill, net of accumulated impairments, ending balance	$ 358,939