Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 06, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity Registrant Name	HORIZON ACQUISITION CORP.
Entity Incorporation, State or Country Code	E9
Entity File Number	001-39465
Entity Tax Identification Number	98-1524224
Entity Address, Address Line One	600 Steamboat Road, Suite 200
Entity Address, City or Town	Greenwich
Entity Address State Or Province	CT
Entity Address, Postal Zip Code	06830
City Area Code	203
Local Phone Number	298-5300
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	true
Entity Central Index Key	0001817071
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
Class A ordinary shares
Document Information [Line Items]
Title of 12(b) Security	Class A ordinary shares included as part of the units
Trading Symbol	HZAC
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		54,398,433
Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50
Document Information [Line Items]
Title of 12(b) Security	Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50
Trading Symbol	HZAC WS
Security Exchange Name	NYSE
Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-third of one redeemable warrant
Document Information [Line Items]
Title of 12(b) Security	Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-third of one redeemable warrant
Trading Symbol	HZAC.U
Security Exchange Name	NYSE
Class B ordinary shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		13,599,608