Document And Entity Information |
Oct. 07, 2026 |
|---|---|
| Document Information [Line Items] | |
| Entity Central Index Key | 0002131072 |
| Document Type | S-1/A |
| Entity Registrant Name | Harbour Island Acquisition Corp. I |
| Entity Incorporation, State or Country Code | DE |
| Entity Filer Category | Non-accelerated Filer |
| Entity Small Business | true |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | true |
| Amendment Description | Amendment No. 1 |
| X | ||||||||||
- Definition Description of changes contained within amended document. No definition available.
|
| X | ||||||||||
- Definition Boolean flag that is true when the XBRL content amends previously-filed or accepted submission. No definition available.
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'. No definition available.
|
| X | ||||||||||
- Definition A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Indicate if registrant meets the emerging growth company criteria. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Indicate if an emerging growth company has elected not to use the extended transition period for complying with any new or revised financial accounting standards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Two-character EDGAR code representing the state or country of incorporation. No definition available.
|
| X | ||||||||||
- Definition The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Indicates that the company is a Smaller Reporting Company (SRC). Reference 1: http://www.xbrl.org/2003/role/presentationRef
|