Restructuring and Other Charges Narrative (Detail) - USD ($)			3 Months Ended		6 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 860,000	$ 7,336,000	$ 1,835,000	$ 8,811,000
Restructuring reserve	$ 3,227,000	$ 5,939,000	2,044,000	7,389,000	2,044,000	7,389,000	$ 1,654,000	$ 2,073,000
Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				7,176,000		8,786,000
Restructuring reserve				7,293,000		7,293,000	1,654,000	1,640,000
Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				160,000		25,000
Restructuring reserve				96,000		96,000	$ 0	$ 433,000
Brooks Life Science Systems
Restructuring Cost and Reserve [Line Items]
Restructuring charges			100,000		200,000
Brooks Semiconductor Solutions Group
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,200,000		1,400,000
Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			900,000
Restructuring reserve			700,000		700,000
Restructuring expected cost			1,300,000		1,300,000
Restructuring expected cost remaining			300,000		300,000
Company-wide Action | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			(500,000)	5,200,000	200,000	5,200,000
Restructuring reserve			0		0
Restructuring cost incurred to date			6,000,000		6,000,000
Actions Initiated in Current Period
Restructuring Cost and Reserve [Line Items]
Restructuring charges				5,200,000
Actions Initiated in Current Period | Brooks Semiconductor Solutions Group
Restructuring Cost and Reserve [Line Items]
Restructuring charges					900,000
Actions Initiated in Prior Periods
Restructuring Cost and Reserve [Line Items]
Restructuring charges				2,100,000		3,600,000
Actions Initiated in Prior Periods | Brooks Life Science Systems
Restructuring Cost and Reserve [Line Items]
Restructuring charges				1,600,000		2,400,000
Actions Initiated in Prior Periods | Brooks Semiconductor Solutions Group
Restructuring Cost and Reserve [Line Items]
Restructuring charges			300,000		500,000	1,200,000
Company-Wide Action & Costs Incurred in Prior Periods | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 6,500,000
Jena, Germany | Brooks Semiconductor Solutions Group | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					300,000
Restructuring reserve			1,200,000		1,200,000
Restructuring expected cost			2,300,000		2,300,000
Restructuring expected cost remaining			200,000		200,000
Jena, Germany | Costs Incurred in Prior Periods | Brooks Semiconductor Solutions Group | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,900,000
Mistelgau, Germany | Brooks Semiconductor Solutions Group | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				400,000	200,000
Restructuring reserve			100,000		100,000
Restructuring cost incurred to date			3,200,000		3,200,000
Mistelgau, Germany | Costs Incurred in Prior Periods | Brooks Semiconductor Solutions Group | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 3,000,000
Spokane, Washington | Brooks Life Science Systems | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				1,600,000
Restructuring reserve			$ 100,000		$ 100,000
Restructuring cost incurred to date				$ 2,400,000		$ 2,400,000