Initial Public Offering (Details) - $ / shares	Jun. 11, 2025	Sep. 30, 2026
Initial Public Offering
Aggregate number of shares purchased	25,300,000
Number of shares per unit	0.5
Warrants exercisable period from IPO	12 months
Warrants exercisable period after the completion of a Business Combination	30 days
Warrants exercisable term	5 years
Public warrants
Initial Public Offering
Warrants exercisable period from IPO	12 months
Warrants exercisable period after the completion of a Business Combination	30 days
Warrants exercisable term	5 years
Class A ordinary shares
Initial Public Offering
Share issue price per share		$ 10
Number of shares for each warrant	1
Exercise price of warrant	$ 11.5
Class A ordinary shares \| Public warrants
Initial Public Offering
Number of shares for each warrant	1
Exercise price of warrant	$ 11.5
IPO
Initial Public Offering
Share issue price per share	$ 10
IPO \| Class A ordinary shares
Initial Public Offering
Number of shares per unit	1
IPO \| Class A ordinary shares \| Public warrants
Initial Public Offering
Number of shares per unit	1
Over-Allotment Option
Initial Public Offering
Aggregate number of shares purchased	3,300,000

Represents the warrants exercisable period after the completion of a Business Combination.

No definition available.

Name:	BLUW_ClassOfWarrantOrRightExercisablePeriodAfterCompletionOfBusinessCombination
Namespace Prefix:	BLUW_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period after the closing of the initial public offering after which public warrants become exercisable.

+ References

No definition available.

+ Details

Name:	BLUW_ClassOfWarrantOrRightExercisablePeriodFromInitialPublicOffering
Namespace Prefix:	BLUW_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the individual quantitative and descriptive elements that provide details of the entity's initial public offering, including amounts, prices, securities issued, proceeds, underwriting fees, and other related disclosures within the IPO table.

+ References

No definition available.

+ Details

Name:	BLUW_DisclosureInitialPublicOfferingLineItems
Namespace Prefix:	BLUW_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares in a unit.

+ References

No definition available.

+ Details

Name:	BLUW_NumberOfSharesPerUnit
Namespace Prefix:	BLUW_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of units issued during period.

+ References

No definition available.

+ Details

Name:	BLUW_NumberOfUnitsIssuedDuringPeriod
Namespace Prefix:	BLUW_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares.

+ References

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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

Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
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: