v3.20.2

Business Combinations - Narrative (Details) customer in Thousands, $ in Millions			3 Months Ended	6 Months Ended	12 Months Ended		16 Months Ended
	Oct. 09, 2019 USD ($)	Feb. 01, 2019 USD ($) customer	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Feb. 01, 2021 USD ($)	Jan. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)
Business Acquisition [Line Items]
Unearned revenue			$ 172.1	$ 172.1	$ 159.1		$ 159.1
DiscoverOrg Holdings
Business Acquisition [Line Items]
Unearned revenue					159.1	$ 52.5	159.1
Pre-Acquisition ZI
Business Acquisition [Line Items]
Unearned revenue									$ 68.3
Komiko
Business Acquisition [Line Items]
Value of consideration transferred	$ 8.5
Potential contingent payments	$ 4.0
Contingent payments attributable to purchase consideration (as a percent)	40.00%
Additional liability recognized relating to contingent payments			0.7	1.7
Fair value of acquired unearned revenue	$ 0.2
Komiko | DiscoverOrg Holdings
Business Acquisition [Line Items]
Value of consideration transferred	8.5
Potential contingent payments					$ 4.0		$ 4.0
Contingent payments attributable to purchase consideration (as a percent)					40.00%		40.00%
Fair value of acquired unearned revenue	0.2
Komiko | Developed technology
Business Acquisition [Line Items]
Identifiable finite-lived intangible assets	$ 2.4
Estimated useful life	7 years
Komiko | Developed technology | DiscoverOrg Holdings
Business Acquisition [Line Items]
Identifiable finite-lived intangible assets	$ 2.4
Estimated useful life	7 years
Pre-Acquisition ZI
Business Acquisition [Line Items]
Value of consideration transferred		$ 760.1
Ownership acquired (as a percent)		100.00%
Number of customers served (over) | customer		8
Transaction costs incurred		$ 2.7
Cash acquired		12.1
Deferred consideration, current		25.0
Fair value of acquired unearned revenue		34.5
Cash, cash equivalents, and restricted cash		12.1
Pre-Acquisition ZI | Accrued expense and other current liabilities
Business Acquisition [Line Items]
Deferred consideration, current			9.8	9.8
Pre-Acquisition ZI | DiscoverOrg Holdings
Business Acquisition [Line Items]
Value of consideration transferred		$ 760.1
Ownership acquired (as a percent)		100.00%
Number of customers served (over) | customer		8
Transaction costs incurred		$ 2.7
Cash acquired		12.1
Deferred consideration, current		25.0
Fair value of acquired unearned revenue		34.5
Fair value adjustment of acquired deferred revenue		$ 33.8
Period to recognize acquired deferred revenue		1 year
Pro forma transaction costs and bonuses						$ 9.2
Cash, cash equivalents, and restricted cash		$ 12.1
Pre-Acquisition ZI | Cash Vesting Payment Program
Business Acquisition [Line Items]
Potential value of future payments			7.1	7.1
Contingent consideration expense			1.5	4.0
Pre-Acquisition ZI | Cash Vesting Payment Program | DiscoverOrg Holdings
Business Acquisition [Line Items]
Potential value of future payments		$ 23.1
Contingent consideration expense					$ 8.8
Pre-Acquisition ZI | Forecast
Business Acquisition [Line Items]
Deferred consideration, noncurrent								$ 10.0
Pre-Acquisition ZI | Forecast | DiscoverOrg Holdings
Business Acquisition [Line Items]
Deferred consideration, noncurrent								$ 10.0
Pre-Acquisition ZI | Developed technology
Business Acquisition [Line Items]
Estimated useful life		5 years 9 months 18 days
Pre-Acquisition ZI | Developed technology | DiscoverOrg Holdings
Business Acquisition [Line Items]
Estimated useful life		5 years 9 months 18 days
NeverBounce
Business Acquisition [Line Items]
Potential contingent payments			$ 1.6	$ 1.6
NeverBounce | DiscoverOrg Holdings
Business Acquisition [Line Items]
Value of consideration transferred					9.6
Potential contingent payments					1.6		$ 1.6			$ 2.0
Transaction costs incurred					0.1		0.1
Fair value of acquired unearned revenue					0.1		0.1
Contingent consideration paid							0.4
NeverBounce | Developed technology | DiscoverOrg Holdings
Business Acquisition [Line Items]
Identifiable finite-lived intangible assets					$ 2.3		$ 2.3
Estimated useful life					7 years

X

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

+ Details

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

+ References

No definition available.

+ Details

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

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

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

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 (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

This element represents the amount of any change recognized during the period in the high-end of the estimated range of outcomes (undiscounted) of a liability assumed in a business combination arising from an item of contingent consideration.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e7008-128479

+ Details

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

X

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

+ Details

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

X

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121647850&loc=d3e4845-128472

+ Details

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

X

- Definition

Amount of deferred revenue expected to be recognized as such within one year or the normal operating cycle, if longer, assumed at the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121647850&loc=d3e4845-128472

+ Details

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

X

- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=121600890&loc=d3e2207-128464

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121647850&loc=d3e4845-128472

+ Details

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

X

- Definition

The cash inflow associated with the acquisition of business during the period (for example, cash that was held by the acquired business).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

+ Details

Name:	us-gaap_CashAcquiredFromAcquisition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130532-203044

+ Details

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

X

- Definition

Amount of cash outflow, made soon after acquisition date of business combination, to settle contingent consideration liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

+ Details

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

X

- Definition

Business Acquisition, Pro Forma Transaction Costs And Bonuses

+ References

No definition available.

+ Details

Name:	zi_BusinessAcquisitionProFormaTransactionCostsAndBonuses
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Business Combination, Contingent Consideration Arrangements, Percentage Of Contingent Payments Attributable To Purchase Consideration

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationContingentConsiderationArrangementsPercentageOfContingentPaymentsAttributableToPurchaseConsideration
Namespace Prefix:	zi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Business Combination, Contingent Consideration, Expense

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationContingentConsiderationExpense
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Business Combination, Contingent Consideration, Potential Future Payments

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationContingentConsiderationPotentialFuturePayments
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Business Combination, Deferred Consideration, Current

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationDeferredConsiderationCurrent
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Business Combination, Deferred Consideration, Noncurrent

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationDeferredConsiderationNoncurrent
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Revenue

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue
Namespace Prefix:	zi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Business Combination, Unearned Revenue Recognition Period

+ References

No definition available.

+ Details

Name:	zi_BusinessCombinationUnearnedRevenueRecognitionPeriod
Namespace Prefix:	zi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number Of Customers Served

+ References

No definition available.

+ Details

Name:	zi_NumberOfCustomersServed
Namespace Prefix:	zi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	dei_LegalEntityAxis=zi_DiscoverOrgHoldingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=zi_PreAcquisitionZoomInformationIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=zi_KomikoLTDMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_DevelopedTechnologyRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=zi_PreAcquisitionZoomInformationIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_AccruedLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=zi_CashVestingPaymentProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=zi_NeverBounceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: