Goodwill and Intangible Assets - Goodwill Roll Forward (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	$ 255,876
Acquisitions and adjustments	234,669
Goodwill, net of accumulated impairments, ending balance	490,545
Brooks Semiconductor Solutions Group
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	47,963
Goodwill, net of accumulated impairments, ending balance	47,963
Brooks Life Sciences
Goodwill [Roll Forward]
Goodwill, net of accumulated impairments, beginning balance	207,913
Acquisitions and adjustments	234,669
Goodwill, net of accumulated impairments, ending balance	$ 442,582