Name:	us-gaap_BusinessCombinationLiabilitiesArisingFromContingenciesAmountRecognizedOtherThanAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Name:	us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)(1)
-URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Name:	us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Business combination contingent consideration equity interests issuable shares.

No definition available.

Name:	zeta_BusinessCombinationContingentConsiderationEquityInterestsIssuableShares
Namespace Prefix:	zeta_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

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

Schedule of acquisition related liabilities .

No definition available.