v3.20.2

Leases - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019 | Dec. 31, 2018
Business Acquisition [Line Items] |  |  |  |  |  |
Sublease, remaining lease term (less than) |  |  | 2 years |  |  |
Rent expense | $ 1.6 | $ 1.2 | $ 3.3 | $ 2.5 |  |
DiscoverOrg Holdings |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Operating lease, remaining lease term |  |  |  |  | 11 years |
Operating lease, option to extend lease, term |  |  |  |  | 5 years |
Rent expense |  |  |  |  | $ 6.5 | $ 1.9
DiscoverOrg Holdings | Minimum |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Sublease, remaining lease term (less than) |  |  |  |  | 1 year |
DiscoverOrg Holdings | Maximum |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Sublease, remaining lease term (less than) |  |  |  |  | 6 years |

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Remaining lease term of operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
Name: | us-gaap_LesseeOperatingLeaseRemainingLeaseTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of operating lease expense. Excludes sublease income. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977 + Details
Name: | us-gaap_OperatingLeaseExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Lessee, Operating Lease, Lease Term, Extension + References No definition available. + Details
Name: | zi_LesseeOperatingLeaseLeaseTermExtension
Namespace Prefix: | zi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessor, Operating Lease, Remaining Sublease Term + References No definition available. + Details
Name: | zi_LessorOperatingLeaseRemainingSubleaseTerm
Namespace Prefix: | zi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=zi_DiscoverOrgHoldingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |