Class of warrants or rights issued during period

No definition available.

Name:	bsaq_ClassOfWarrantsOrRightsIssuedDuringPeriod
Namespace Prefix:	bsaq_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Class of warrants or rights issued during period price per warrant issued

+ References

No definition available.

+ Details

Name:	bsaq_ClassOfWarrantsOrRightsIssuedDuringPeriodPricePerWarrantIssued
Namespace Prefix:	bsaq_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow associated with the amount received from entity's first offering of stock to the public.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

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

- Definition

The cash inflow associated with the amount received from entity's raising of capital via private rather than public placement.

+ References

+ Details

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

- Definition

The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

+ References

+ Details

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

- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of new stock issued during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_PrivatePlacementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=bsaq_PrivatePlacementWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=bsaq_PublicSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=bsaq_SponsorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=bsaq_OptionUnitsUnitsSoldAtOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=bsaq_UnderwritersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events - Additional Information (Detail) - USD ($)			4 Months Ended
	Aug. 03, 2021	Jul. 20, 2021	Jun. 30, 2021
Subsequent Event [Line Items]
Shares issued, price per share		$ 10.00
IPO [Member] \| Warrant [Member]
Subsequent Event [Line Items]
Class of warrants or rights issued during period			13,500,000
Private Placement [Member] \| Warrant [Member] \| Private Placement Warrants [Member]
Subsequent Event [Line Items]
Class of warrants or rights issued during period			6,000,000
Subsequent Event [Member] \| IPO [Member] \| Public Shares [Member]
Subsequent Event [Line Items]
Stock issued during period, shares		15,000,000
Proceeds from initial public offering		$ 150,000,000
Shares issued, price per share		$ 10.00
Subsequent Event [Member] \| Private Placement [Member] \| Warrant [Member] \| Private Placement Warrants [Member] \| Sponsor [Member]
Subsequent Event [Line Items]
Class of warrants or rights issued during period		6,000,000
Class of warrants or rights issued during period, price per warrant issued		$ 1.00
Proceeds from private placement		$ 6,000,000
Subsequent Event [Member] \| Over-Allotment Option [Member] \| Private Placement Warrants [Member]
Subsequent Event [Line Items]
Class of warrants or rights issued during period	380,000
Subsequent Event [Member] \| Over-Allotment Option [Member] \| Warrant [Member] \| Private Placement Warrants [Member] \| Sponsor [Member]
Subsequent Event [Line Items]
Class of warrants or rights issued during period	380,000
Class of warrants or rights issued during period, price per warrant issued	$ 1.00
Subsequent Event [Member] \| Over-Allotment Option [Member] \| Option Units Units Sold At Option [Member] \| Underwriters [Member]
Subsequent Event [Line Items]
Stock issued during period for services, shares	1,900,000
Shares issued, price per share	$ 10.00
Proceeds from issuance of equity	$ 19,000,000