Goodwill and Intangible Assets Components of Goodwill by Business Segment (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Goodwill [Roll Forward]
Gross goodwill, period start	$ 736,366	$ 724,459
Less: aggregate impairment charges recorded	(614,958)	(614,958)	$ (614,958)
Goodwill, less accumulated impairments	202,386	121,408	109,501
Acquisitions and adjustments	80,978	11,907
Gross goodwill, period end	817,344	736,366
Brooks Semiconductor Solutions Group
Goodwill [Roll Forward]
Gross goodwill, period start	654,727	651,067
Less: aggregate impairment charges recorded	(588,944)	(588,944)	(588,944)
Goodwill, less accumulated impairments	66,833	65,783	62,123
Acquisitions and adjustments	1,050	3,660
Gross goodwill, period end	655,777	654,727
Brooks Life Science Systems
Goodwill [Roll Forward]
Gross goodwill, period start	55,625	47,378
Less: aggregate impairment charges recorded	0	0	0
Goodwill, less accumulated impairments	135,553	55,625	47,378
Acquisitions and adjustments	79,928	8,247
Gross goodwill, period end	135,553	55,625
Other
Goodwill [Roll Forward]
Gross goodwill, period start	26,014	26,014
Less: aggregate impairment charges recorded	(26,014)	(26,014)	(26,014)
Goodwill, less accumulated impairments	0	0	$ 0
Acquisitions and adjustments	0	0
Gross goodwill, period end	$ 26,014	$ 26,014