Debt instrument maturity year.

No definition available.

Name:	nlsnnv_DebtInstrumentMaturityYear
Namespace Prefix:	nlsnnv_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

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

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_LIBORBasedVariableRateOfOnePointEightFivePercentageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_LIBORBasedVariableRateOfTwoPointOneZeroPercentageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_EuroLIBORBasedVariableRateOfTwoPointFiveZeroPercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorSecuredTermLoanDueTwoThousandAndTwentyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_EuroLIBORBasedVariableRateOfThreePointSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_LIBORBasedVariableRateOfFourPointSevenFivePercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorSecuredRevolvingCreditFacilityDueTwoThousandAndTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nlsnnv_EuroLIBOROrLIBORBasedVariableRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorDebentureLoanDueTwoThousandAndTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorDebentureLoanDueTwoThousandAndTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorDebentureLoanDueTwoThousandAndTwentyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorDebentureLoanDueTwoThousandAndTwentyEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=nlsnnv_SeniorDebentureLoanDueTwoThousandAndThirtyMember
Namespace Prefix:
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Long-term Debt and Other Financing Arrangements - Summary of Long-Term Debt (Parenthetical) (Detail) € in Millions, $ in Millions			3 Months Ended	12 Months Ended
	Mar. 21, 2021	Mar. 16, 2021	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2021 EUR (€)	Dec. 31, 2020 EUR (€)
Senior Secured Term Loan Facility Due 2023
Debt Instrument [Line Items]
Debt instrument, maturity year		2023
Senior Secured Term Loan Facility Due 2023 \| LIBOR Based Variable Rate of 1.85%
Debt Instrument [Line Items]
Debt instrument face value			$ 1,125	$ 1,125
Debt instrument, variable rate			1.85%	1.85%
Debt instrument, maturity year			2023	2023
Senior Secured Term Loan Facility Due 2023 \| LIBOR Based Variable Rate of 2.10%
Debt Instrument [Line Items]
Debt instrument face value			$ 2,303	$ 2,303
Debt instrument, variable rate			2.10%	2.10%
Debt instrument, maturity year			2023	2023
Senior Secured Term Loan Facility Due 2023 \| Euro LIBOR Based Variable Rate of 2.50%
Debt Instrument [Line Items]
Debt instrument face value \| €					€ 545	€ 545
Debt instrument, variable rate			2.50%	2.50%
Debt instrument, maturity year			2023	2023
Senior Secured Term Loan Facility Due 2025
Debt Instrument [Line Items]
Debt instrument, maturity year		2023
Senior Secured Term Loan Facility Due 2025 \| Euro LIBOR Based Variable Rate of 3.75%
Debt Instrument [Line Items]
Debt instrument face value \| €					€ 660	€ 660
Debt instrument, variable rate			3.75%	3.75%
Debt instrument, maturity year			2025	2025
Senior Secured Term Loan Facility Due 2025 \| LIBOR Based Variable Rate of 4.75%
Debt Instrument [Line Items]
Debt instrument face value			$ 550	$ 550
Debt instrument, variable rate			4.75%	4.75%
Debt instrument, maturity year			2025	2025
Senior Secured Revolving Credit Facility Due 2023 \| Euro LIBOR or LIBOR Based Variable Rate
Debt Instrument [Line Items]
Debt instrument face value			$ 850	$ 850
Debt instrument, maturity year			2023	2023
Senior Debenture Loan Due 2021
Debt Instrument [Line Items]
Debt instrument face value			$ 425	$ 425
Debt instrument, maturity year	2021		2021	2021
Debt instrument interest rate stated percentage	5.50%		5.50%	5.50%	5.50%	5.50%
Senior Debenture Loan Due 2022
Debt Instrument [Line Items]
Debt instrument face value			$ 825	$ 825
Debt instrument, maturity year			2022	2022
Debt instrument interest rate stated percentage			5.00%	5.00%	5.00%	5.00%
Senior Debenture Loan Due 2025
Debt Instrument [Line Items]
Debt instrument face value			$ 500	$ 500
Debt instrument, maturity year			2025	2025
Debt instrument interest rate stated percentage			5.00%	5.00%	5.00%	5.00%
Senior Debenture Loan Due 2028
Debt Instrument [Line Items]
Debt instrument face value			$ 1,000	$ 1,000
Debt instrument, maturity year			2028	2028
Debt instrument interest rate stated percentage			5.625%	5.625%	5.625%	5.625%
Senior Debenture Loan Due 2030
Debt Instrument [Line Items]
Debt instrument face value			$ 750	$ 750
Debt instrument, maturity year			2030	2030
Debt instrument interest rate stated percentage			5.875%	5.875%	5.875%	5.875%