Date when the business acquisition agreement was executed, in YYYY-MM-DD format.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares of equity interests issued or issuable to acquire entity.

+ References

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-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Name of the acquired entity.

+ References

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-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of acquired receivable from business combination, excluding certain loans and debt securities acquired in transfer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

+ Details

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

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

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-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

+ References

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-SubTopic 20
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-Paragraph 1
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

+ References

+ Details

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

- Definition

The amount of property, plant, and equipment recognized as of the acquisition date.

+ References

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-SubTopic 10
-Section 55
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

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-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
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-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

+ Details

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

- Definition

Acquisitions

+ References

No definition available.

+ Details

Name:	zeta_AcquisitionsLineItems
Namespace Prefix:	zeta_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Bisness acquisition holdbacks.

+ References

No definition available.

+ Details

Name:	zeta_BisnessAcquisitionHoldbacks
Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Business combination, estimated fair value of earn outs from operating performance.

+ References

No definition available.

+ Details

Name:	zeta_BusinessCombinationEstimatedFairValueOfEarnOutsFromOperatingPerformance
Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business combination payments to acquire businesses gross.

+ References

No definition available.

+ Details

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Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business combination payments to acquire cash.

+ References

No definition available.

+ Details

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Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business combination recognized identifiable assets acquired and liabilities assumed other net asset.

+ References

No definition available.

+ Details

Name:	zeta_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNetAsset
Namespace Prefix:	zeta_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Period Type:

Acquisition - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Oct. 07, 2024	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Sep. 30, 2024
Business Acquisition, Date of Acquisition Agreement
Business acquisition, net of cash acquired		$ 530	$ 0
Recognized of customer relationships as goodwill		325,999		$ 325,992	$ 325,999
Acquisition-related liabilities paid		7,863
LiveIntent, Inc [Member]
Business Acquisition, Date of Acquisition Agreement
Date of agreement	Oct. 07, 2024
Name of acquired entity	LiveIntent, Inc.
Fair value of aggregate purchase consideration	$ 285,982
Amount paid for cash acquired	26,983
Fair value of earn outs	16,898
Business acquisiton holdbacks	14,350
Business acquisition, net of cash acquired	55,819
Recognized of customer relationships intangibles	29,760
Business combination, recognized identifiable assets acquired and liabilities assumed, property, plan and equipment	36,180
Recognized of customer relationships as goodwill	185,091
Other net assets	$ 22,731
Finite lived intangible assets useful lives	4 years
Acquisition-related liabilities paid		$ 530
Acquisition-related expenses	$ 8,229
LiveIntent, Inc [Member] \| Tradenames [Member]
Business Acquisition, Date of Acquisition Agreement
Business combination, recognized identifiable assets acquired and liabilities assumed, indefinite lived intangible assets	$ 12,220
LiveIntent, Inc [Member] \| Class A Common Stock [Member]
Business Acquisition, Date of Acquisition Agreement
Business acquisition, number of shares	5,839,656