Represents the increase (decrease) in the estimated project cost based on forecast revisions.

No definition available.

Name:	flr_ChangeInForecastEstimateIncreaseDecreaseInProjectCost
Namespace Prefix:	flr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the increase (decrease) in estimated petrochemical project cost based on forecast revisions, in dollars per diluted share.

+ References

No definition available.

+ Details

Name:	flr_ChangeInForecastEstimateIncreaseDecreaseInProjectCostPerDilutedShare
Namespace Prefix:	flr_
Data Type:	dtr-types1:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Charges From Write-Off of Embedded Foreign Currency Derivatives

+ References

No definition available.

+ Details

Name:	flr_ChargesFromWriteOffOfEmbeddedForeignCurrencyDerivatives
Namespace Prefix:	flr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number Of Project

+ References

No definition available.

+ Details

Name:	flr_NumberOfProject
Namespace Prefix:	flr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Reduction in cash due to no longer including the former subsidiary's cash in the consolidated entity's cash.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-13

+ Details

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

- Definition

Amount of foreign currency translation gain (loss) in the disposal group, including discontinued operation, recognized in the statement of income as a result of the sale or complete or substantially complete liquidation of an investment in a foreign entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 20
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481694/830-30-45-20

+ Details

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

- Definition

The difference between the carrying value and the sale price of an investment. A loss would be recognized when the sale price of the investment is less than the carrying value of the investment. This element refers to the Loss included in earnings and not to the cash proceeds of the sale.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(7)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(9)(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

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

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-12

+ Details

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

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

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=flr_AMECOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=flr_EnergySolutionsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsAxis=flr_UpstreamProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=flr_UrbanSolutionsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsAxis=flr_LAXAutomatedPeopleMoverProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsAxis=flr_HighwayProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsAxis=flr_InternationalBridgeProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=flr_MissionSolutionsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsAxis=flr_WeaponsFacilityProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Operating Information by Segment and Geographic Area - Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) segment	Sep. 30, 2023 USD ($) $ / shares	Sep. 30, 2022 USD ($) segment $ / shares
Disposal Group, Not Discontinued Operations \| AMECO
Segment Reporting Information [Line Items]
Proceeds from divestiture of businesses			$ 144
Cash divestiture			17
Loss on sale			60
AMECO divestiture, negative impact on earnings from foreign currency translation			35
Energy Solutions
Segment Reporting Information [Line Items]
Expense from embedded foreign currency derivatives	$ 24	$ (5)
Energy Solutions \| Upstream Project
Segment Reporting Information [Line Items]
Effect of forecast revision on estimated project cost			$ 58
Effect of forecast revision on estimated project cost (in dollars per share) \| $ / shares			$ 0.34
Urban Solutions
Segment Reporting Information [Line Items]
Number of project \| segment		3		3
Urban Solutions \| LAX Automated People Mover Project
Segment Reporting Information [Line Items]
Effect of forecast revision on estimated project cost			$ 59	$ 35
Effect of forecast revision on estimated project cost (in dollars per share) \| $ / shares			$ 0.34	$ 0.20
Urban Solutions \| Highway Project
Segment Reporting Information [Line Items]
Effect of forecast revision on estimated project cost				$ 86
Effect of forecast revision on estimated project cost (in dollars per share) \| $ / shares				$ 0.50
Urban Solutions \| International Bridge Project
Segment Reporting Information [Line Items]
Effect of forecast revision on estimated project cost				$ 54
Effect of forecast revision on estimated project cost (in dollars per share) \| $ / shares				$ 0.23
Mission Solutions \| Weapons Facility Project
Segment Reporting Information [Line Items]
Effect of forecast revision on estimated project cost			$ 30
Effect of forecast revision on estimated project cost (in dollars per share) \| $ / shares			$ 0.17