Cover - shares	9 Months Ended
	Jun. 30, 2026	Jul. 22, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Jun. 30, 2026
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q3
Entity Registrant Name	Eureka Acquisition Corp
Entity Central Index Key	0002000410
Entity Tax Identification Number	00-0000000
Current Fiscal Year End Date	--09-30
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity File Number	001-42152
Entity Shell Company	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	true
Entity Incorporation, State or Country Code	E9
Entity Address, Address Line One	14 Prudential Tower
Entity Address, City or Town	Singapore
Entity Address, Country	SG
Entity Address, Postal Zip Code	049712
City Area Code	(+1)
Local Phone Number	949 899 1827
Units, consisting of one Ordinary Share, $0.0001 par value, and one Right to acquire one-fifth of one Ordinary Share
Document Information [Line Items]
Title of 12(b) Security	Units, consisting of one Ordinary Share, $0.0001 par value, and one Right to acquire one-fifth of one Ordinary Share
Trading Symbol	EURKU
Security Exchange Name	NASDAQ
Class A ordinary shares, par value $0.0001 per share
Document Information [Line Items]
Title of 12(b) Security	Class A ordinary shares, par value $0.0001 per share
Trading Symbol	EURK
Security Exchange Name	NASDAQ
Rights, each whole right to acquire one-fifth of one Class A ordinary share
Document Information [Line Items]
Title of 12(b) Security	Rights, each whole right to acquire one-fifth of one Class A ordinary share
Trading Symbol	EURKR
Security Exchange Name	NASDAQ
Class A Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		733,101
Class B Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,437,500