Goodwill and Intangible Assets - Components of Goodwill by Operating Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Goodwill [Line Items]
Gross goodwill	$ 1,115,020	$ 1,103,560
Accumulated goodwill impairments	(614,958)	(614,958)
Goodwill	500,062	488,602
Brooks Semiconductor Solutions Group
Goodwill [Line Items]
Gross goodwill	637,107	636,791
Accumulated goodwill impairments	(588,944)	(588,944)
Goodwill	48,163	47,847
Brooks Life Sciences
Goodwill [Line Items]
Gross goodwill	451,899	440,755
Goodwill	451,899	440,755
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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Amount before 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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