Revised Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011
Condensed Financial Statements, Captions [Line Items]
Equity investments in joint ventures	$ 35,785	$ 34,950
Total assets	645,323	636,958
Accumulated other comprehensive income	13,429	17,324
Accumulated deficit	(1,103,435)	(1,108,105)
Total Brooks Automation, Inc. stockholders' equity	524,949	518,347
Total equity	525,548	518,936
Total liabilities and equity	645,323	636,958
As Previously Reported
Condensed Financial Statements, Captions [Line Items]
Equity investments in joint ventures		34,612
Total assets		636,620
Accumulated other comprehensive income		19,480
Accumulated deficit		(1,110,599)
Total Brooks Automation, Inc. stockholders' equity		518,009
Total equity		518,598
Total liabilities and equity		636,620
Adjustment
Condensed Financial Statements, Captions [Line Items]
Equity investments in joint ventures		338
Total assets		338
Accumulated other comprehensive income		(2,156)
Accumulated deficit		2,494
Total Brooks Automation, Inc. stockholders' equity		338
Total equity		338
Total liabilities and equity		$ 338