Derivative Financial Instruments - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($) contract counterparty	Dec. 31, 2023 USD ($) contract
Derivative [Line Items]
Number of counterparties, net exposure threshold set to zero \| counterparty	1
All counterparties except one
Derivative [Line Items]
Counterparties, collateral required threshold	0.00%
Other embedded derivatives
Derivative [Line Items]
Term of contract, term one	1 year
Term of contract, term two	2 years
Term of contract, term three	3 years
Term of contract, term five	5 years
Term of contract, term six	6 years
Call options and interest rate swaps \| Derivatives for Trading and Investment \| Not Designated as Hedging Instrument
Derivative [Line Items]
Collateral posted	$ 771	$ 775
Net Credit Risk	34	39
Call options and interest rate swaps \| Cash and Cash Equivalents \| Not Designated as Hedging Instrument
Derivative [Line Items]
Collateral posted	$ 679	$ 588
Futures contracts
Derivative [Line Items]
Number of instruments held \| contract	527	439
Collateral held	$ 7	$ 4

Derivative, Term of Contract, Term Five

No definition available.

Name:	fnf_DerivativeTermOfContractTermFive
Namespace Prefix:	fnf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative, Term Of Contract, Term One

+ References

No definition available.

+ Details

Name:	fnf_DerivativeTermOfContractTermOne
Namespace Prefix:	fnf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative, Term Of Contract, Term Six

+ References

No definition available.

+ Details

Name:	fnf_DerivativeTermOfContractTermSix
Namespace Prefix:	fnf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative, Term Of Contract, Term Three

+ References

No definition available.

+ Details

Name:	fnf_DerivativeTermOfContractTermThree
Namespace Prefix:	fnf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative, Term Of Contract, Term Two

+ References

No definition available.

+ Details

Name:	fnf_DerivativeTermOfContractTermTwo
Namespace Prefix:	fnf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivatives, Collateral, Net Exposure Threshold for Which Collateral Required

+ References

No definition available.

+ Details

Name:	fnf_DerivativesCollateralNetExposureThresholdForWhichCollateralRequired
Namespace Prefix:	fnf_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Counterparties, Net Exposure Threshold Not Set to Zero

+ References

No definition available.

+ Details

Name:	fnf_NumberOfCounterpartiesNetExposureThresholdNotSetToZero
Namespace Prefix:	fnf_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4H

+ Details

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

- Definition

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480463/815-10-45-5

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-SubTopic 20
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

+ Details

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

- Definition

Fair value, after effect of master netting arrangement and deduction of obligation to return financial collateral not offset and financial instrument subject to master netting arrangement not offset, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and contract can be net settled by means outside contract or delivery of asset. Includes derivative not subject to master netting arrangement or similar agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 13
-SubTopic 20
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-13

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

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

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478795/946-210-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 55
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477439/946-210-55-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column A)(Footnote 3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column C))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5A
-Subparagraph (SX 210.12-13A(Column B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5A

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_CounterpartyNameAxis=fnf_AllCounterpartiesExceptOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EmbeddedDerivativeFinancialInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=fnf_CallOptionsAndInterestRateSwapsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_FutureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: