Business Combinations - Components of Finite-Lived Intangible Assets Acquired (Details) - USD ($) $ in Millions		12 Months Ended
Feb. 01, 2019	Dec. 31, 2019
Pre-Acquisition ZI
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 322.0
Pre-Acquisition ZI \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets	322.0
Pre-Acquisition ZI \| Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value	$ 116.0
Weighted Average Useful Life	5 years 9 months 18 days
Pre-Acquisition ZI \| Developed technology \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value	$ 116.0
Weighted Average Useful Life	5 years 9 months 18 days
Pre-Acquisition ZI \| Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value	$ 173.0
Weighted Average Useful Life	15 years
Pre-Acquisition ZI \| Customer relationships \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value	$ 173.0
Weighted Average Useful Life	15 years
NeverBounce \| Developed technology \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value		$ 2.3
Weighted Average Useful Life		7 years
NeverBounce \| Customer relationships \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value		$ 1.1
Weighted Average Useful Life		5 years
NeverBounce \| Brand portfolio \| DiscoverOrg Holdings
Acquired Finite-Lived Intangible Assets [Line Items]
Fair Value		$ 0.2
Weighted Average Useful Life		7 years

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.

No definition available.

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- 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

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- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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- Definition

Finite And Indefinite Lived Intangible Assets Acquired

+ References

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