Goodwill and Intangible Assets - Components of Goodwill by Operating Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Goodwill [Line Items]
Gross goodwill	$ 1,166,284	$ 1,116,494
Accumulated goodwill impairments	(614,958)	(614,958)
Goodwill	551,326	501,536
Brooks Semiconductor Solutions Group
Goodwill [Line Items]
Gross goodwill	670,214	637,303
Accumulated goodwill impairments	(588,944)	(588,944)
Goodwill	81,270	48,359
Brooks Life Sciences Products
Goodwill [Line Items]
Gross goodwill	110,771	103,278
Goodwill	110,771	103,278
Brooks Life Sciences Services
Goodwill [Line Items]
Gross goodwill	359,285	349,899
Goodwill	359,285	349,899
Other
Goodwill [Line Items]
Gross goodwill	26,014	26,014
Accumulated goodwill impairments	$ (26,014)	$ (26,014)

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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