Acquisitions and Divestiture - Pro Forma Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Crossing Automation Inc
Business Acquisition [Line Items]
Revenue	$ 453,045	$ 570,864
Net income (loss) attributable to Brooks Automation, Inc.	(3,216)	135,245
Nexus
Business Acquisition [Line Items]
Revenue		720,989
Net income (loss) attributable to Brooks Automation, Inc.		$ 124,114