Discontinued Operations - Non-cash Items and Capital Expenditures (Details) - Semiconductor Cryogenics Business - Held-for-sale - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Discontinued Operation, Alternative Cash Flow Information [Abstract]
Depreciation and amortization	$ 743	$ 919	$ 1,034
Capital expenditures	302	1,049	560
Stock-based compensation	966	705	460
Earnings of equity method investment	$ (6,788)	$ (9,834)	$ (3,445)

Discontinued Operation Earnings Losses of Equity Method Investments

No definition available.

Name:	brks_DiscontinuedOperationEarningsLossesOfEquityMethodInvestments
Namespace Prefix:	brks_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Stock Based Compensation Discontinued Operations

+ References

No definition available.

+ Details

Name:	brks_StockBasedCompensationDiscontinuedOperations
Namespace Prefix:	brks_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of capital expenditure attributable to discontinued operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

+ Details

Name:	us-gaap_CapitalExpenditureDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of deprecation and amortization expense attributable to property, plant and equipment and intangible assets of discontinued operations.

+ References

+ Details

Name:	us-gaap_DepreciationAndAmortizationDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_DiscontinuedOperationAlternativeCashFlowInformationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=brks_SemiconductorCryogenicsBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsHeldforsaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: