Percentage of public shares to be redeemed on non completion of business combination.

No definition available.

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Namespace Prefix:	onch_
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- 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.

+ References

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+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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- 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

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- Definition

The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt).

+ References

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- Details

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Private Placement (Details) - USD ($)		6 Months Ended	12 Months Ended
Private Placement (Details) - USD ($)	Jul. 03, 2025	Jun. 30, 2026	Dec. 31, 2025
Private Placement [Line Items]
Price per warrant		$ 2
Proceeds allocated to public warrants			$ 1,854,375
Percentage of public shares to be redeemed on business combination	100.00%
Sponsor [Member]
Private Placement [Line Items]
Number of shares per warrant	2,250,000
Percentage of public shares to be redeemed on business combination		100.00%
Private Placement Warrants [Member]
Private Placement [Line Items]
Number of shares per warrant	2,250,000
Private Placement Warrants [Member] \| Sponsor [Member]
Private Placement [Line Items]
Number of shares per warrant	1,500,000
Private Placement Warrants [Member] \| Cantor Fitzgerald Co [Member]
Private Placement [Line Items]
Number of shares per warrant	750,000
Class A Ordinary Shares [Member]
Private Placement [Line Items]
Number of shares per warrant	1
Price per warrant	$ 11.5	$ 11.5
Class A Ordinary Shares [Member] \| Private Placement Warrants [Member]
Private Placement [Line Items]
Price per warrant	$ 11.5
Private Placement [Member] \| Private Placement Warrants [Member]
Private Placement [Line Items]
Number of shares per warrant	2,250,000
Price per warrant	$ 2
Proceeds allocated to public warrants	$ 4,500,000
Private Placement [Member] \| Private Placement Warrants [Member] \| Sponsor [Member]
Private Placement [Line Items]
Number of shares per warrant	1,500,000