Revised Consolidated Statement of Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Equity in earnings of joint ventures	$ 2,133	$ 4,815	$ 1,074
Net income	136,835	130,437	59,884
Net income attributable to Brooks Automation, Inc.	136,789	130,385	59,841
Net income per share attributable to Brooks Automation, Inc. common shareholders:
Basic	$ 2.10	$ 2.02	$ 0.94
Diluted	$ 2.08	$ 2.01	$ 0.93
As Previously Reported
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Equity in earnings of joint ventures		2,782	215
Net income		128,404	59,025
Net income attributable to Brooks Automation, Inc.		128,352	58,982
Net income per share attributable to Brooks Automation, Inc. common shareholders:
Basic		$ 1.99	$ 0.92
Diluted		$ 1.97	$ 0.92
Adjustment
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Equity in earnings of joint ventures		2,033	859
Net income		2,033	859
Net income attributable to Brooks Automation, Inc.		$ 2,033	$ 859
Net income per share attributable to Brooks Automation, Inc. common shareholders:
Basic		$ 0.03	$ 0.01
Diluted		$ 0.03	$ 0.01