Restructuring and Other Charges - General Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3,226	$ 12,039	$ 4,713
Accrued restructuring costs	1,708	5,939	2,073	$ 3,475
Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,226	12,014	3,400
Accrued restructuring costs	1,708	5,939	1,640	3,404
Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		25	1,300
Accrued restructuring costs		0	433	$ 71
Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2,200
Brooks Semiconductor Solutions Group | Facilities and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,300
Brooks Life Science Systems | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1,300
Actions Initiated During and Prior to Fiscal Year 2017, Excluding Company-wide Actions | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,600
Actions Initiated During and Prior to Fiscal Year 2017, Excluding Company-wide Actions | Brooks Life Science Systems | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	400
Streamline Service Operations, Initiated Fiscal Year 2017 | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,600
Restructuring expected cost	1,600
Accrued restructuring costs	500
Actions Initiated During Fiscal Year 2016 | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10,800
Actions Initiated During Fiscal Year 2016, Excluding Company-wide Actions | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,000
Actions Initiated During Fiscal Year 2016, Excluding Company-wide Actions | Brooks Life Science Systems | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3,100
Reduce Global Footprint and Streamline Cost Structure, Initiated Fiscal Year 2016 | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	800	1,800
Accrued restructuring costs	1,000
Restructuring cost incurred to date	2,600
Integration of Contact Acquisition Initiated in Fiscal Year 2016 | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	200
Streamlining Segment Structure, Integrating Acquisition, and Facility Closure, Initiated in Fiscal Year 2016 | Brooks Life Science Systems | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	200	3,100
Accrued restructuring costs	0	500
Restructuring cost incurred to date	3,300
Company-wide Action Initiated in Fiscal Year 2016 | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	300	5,800
Accrued restructuring costs	0
Restructuring cost incurred to date	6,100
Actions Initiated Prior to Fiscal Year 2016
Restructuring Cost and Reserve [Line Items]
Accrued restructuring costs	$ 0	200
Actions Initiated Prior to Fiscal Year 2016 | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,300
Actions Initiated Prior to Fiscal Year 2016 | Brooks Semiconductor Solutions Group
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,200
Maximum | Actions Initiated Prior to Fiscal Year 2016 | Brooks Life Science Systems
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 100