Acquisition Related Liabilities - Additional Information (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
eBay CRM [Member]
Schedule of acquisition related liabilities [Line Items]
Business combination final contingent consideration paid	$ 0

Business combination final contingent consideration payable in cash.

No definition available.

Name:	zeta_BusinessCombinationFinalContingentConsiderationPayableInCash
Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant