Fair Value of Financial Instruments - Schedule of Carrying Value and Estimated Fair Value of Financial Instruments Carried at Other Than Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Assets
Investments in unconsolidated affiliates	$ 3,874	$ 3,334
Trade and notes receivables, net of allowance	443	442
Total
Total Estimated Fair Value
Assets
FHLB common stock	153	138
Commercial mortgage loans	2,342	2,253
Residential mortgage loans	2,830	2,545
Investments in unconsolidated affiliates	3,394	2,786
Policy loans	94	71
Other invested assets	69	397
Company-owned life insurance	426	59
Trade and notes receivables, net of allowance	443	442
Total	9,751	8,691
Liabilities
Investment contracts, included in contractholder funds	44,762	40,229
Debt	3,986	3,568
Total	48,748	43,797
Carrying Amount
Assets
FHLB common stock	153	138
Commercial mortgage loans	2,572	2,538
Residential mortgage loans	3,054	2,798
Investments in unconsolidated affiliates	3,394	2,786
Policy loans	94	71
Other invested assets	69	397
Company-owned life insurance	426	59
Trade and notes receivables, net of allowance	443	442
Total	10,205	9,229
Liabilities
Investment contracts, included in contractholder funds	55,057	44,540
Debt	4,186	3,887
Total	59,243	48,427
Level 1
Assets
FHLB common stock	0	0
Commercial mortgage loans	0	0
Residential mortgage loans	0	0
Investments in unconsolidated affiliates	0	0
Policy loans	0	0
Other invested assets	22	0
Company-owned life insurance	0	17
Trade and notes receivables, net of allowance	0	0
Total	22	17
Liabilities
Investment contracts, included in contractholder funds	0	0
Debt	0	0
Total	0	0
Level 2
Assets
FHLB common stock	153	138
Commercial mortgage loans	0	0
Residential mortgage loans	0	0
Investments in unconsolidated affiliates	0	0
Policy loans	0	0
Other invested assets	0	0
Company-owned life insurance	0	0
Trade and notes receivables, net of allowance	0	0
Total	153	138
Liabilities
Investment contracts, included in contractholder funds	0	0
Debt	3,986	3,568
Total	3,986
Level 3
Assets
FHLB common stock	0	0
Commercial mortgage loans	2,342	2,253
Residential mortgage loans	2,830	2,545
Investments in unconsolidated affiliates	4	7
Policy loans	94	71
Other invested assets	0	397
Company-owned life insurance	426	0
Trade and notes receivables, net of allowance	443	442
Total	6,139	5,715
Liabilities
Investment contracts, included in contractholder funds	44,762	40,229
Debt	0	0
Total	44,762	40,229
NAV
Assets
Investments in unconsolidated affiliates	3,390	2,779
Other invested assets	47	42
Total	$ 3,437	$ 2,821

Assets, Carried On Balance Sheet At Other Than Fair Value, Amount

No definition available.

Name:	fnf_AssetsCarriedOnBalanceSheetAtOtherThanFairValueAmount
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

FHLB Common Stock, Fair Value

+ References

No definition available.

+ Details

Name:	fnf_FHLBCommonStockFairValue
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments, Affiliated Bank Loan, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	fnf_InvestmentsAffiliatedBankLoanFairValueDisclosure
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the investment commercial mortgage loan portfolio

+ References

No definition available.

+ Details

Name:	fnf_InvestmentsCommercialMortgageLoansFairValueDisclosure
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the investment residential mortgage loan portfolio

+ References

No definition available.

+ Details

Name:	fnf_InvestmentsResidentialMortgageLoansFairValueDisclosure
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Liabilities, Carried On Balance Sheet At Amounts Other Than Fair Value

+ References

No definition available.

+ Details

Name:	fnf_LiabilitiesCarriedOnBalanceSheetAtAmountsOtherThanFairValue
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Policy Loans, Fair Value

+ References

No definition available.

+ Details

Name:	fnf_PolicyLoansFairValue
Namespace Prefix:	fnf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of accounts and financing receivable. Includes, but is not limited to, notes and loan receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

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

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69B

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1D
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1D

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

+ Details

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

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481664/323-10-45-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(10))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 25
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-25

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Fair value portion of liability related to investment contracts for example, but not limited to, guaranteed investment contract or annuities.

+ References

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: