Goodwill and Intangible Assets Components of Goodwill by Business Segment (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2016	Sep. 30, 2015	Feb. 01, 2016	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	202,347	121,408	$ 24,000	109,501
Acquisitions and adjustments	80,939	11,907
Gross goodwill, period end	817,305	736,366
Brooks Product Solutions
Goodwill [Roll Forward]
Gross goodwill, period start	497,935	494,275
Less: aggregate impairment charges recorded	(437,706)	(437,706)		(437,706)
Goodwill, less accumulated impairments	61,279	60,229		56,569
Acquisitions and adjustments	1,050	3,660
Gross goodwill, period end	498,985	497,935
Brooks Global Services
Goodwill [Roll Forward]
Gross goodwill, period start	156,792	156,792
Less: aggregate impairment charges recorded	(151,238)	(151,238)		(151,238)
Goodwill, less accumulated impairments	5,554	5,554		5,554
Acquisitions and adjustments	0	0
Gross goodwill, period end	156,792	156,792
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	135,514	55,625		47,378
Acquisitions and adjustments	79,889	8,247
Gross goodwill, period end	135,514	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