Restructuring and Other Charges - General Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 714	$ 3,144	$ 10,210
Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 714	3,144	10,185
Corporate, Non-Segment | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			300
Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 300		2,500
Brooks Life Sciences | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 300		400
Actions Initiated During Fiscal Year 2017 | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,500
Actions Initiated During Fiscal Year 2016 | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				8,900
Actions Initiated During Fiscal Year 2016 | Corporate, Non-Segment | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				4,500
Actions Initiated During Fiscal Year 2016 | Brooks Semiconductor Solutions Group | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1,000	1,200
Actions Initiated During Fiscal Year 2016 | Brooks Life Sciences | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				3,100
Actions Initiated Prior to Fiscal Year 2016 | Workforce-related termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 1,300