Revenue - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,470.1	$ 1,755.5
Contract liabilities	3,914.2	3,314.2
Net contract assets (liabilities)	(2,444.1)	$ (1,558.7)
Contract assets, increase (decrease)	(285.4)
Contract liabilities, increase (decrease)	600.0
Net contract assets (liabilities), increase (decrease)	$ (885.4)
Contract assets, increase (decrease), percent	(16.30%)
Contract liabilities, increase (decrease), percent	18.10%
Net contract assets (liabilities), increase (decrease), percent	56.80%
Deferred revenue, revenue recognized	$ 836.3
Performance obligation satisfied in previous periods	$ 88.2

Billings in Excess of Cost, Current, Increase (Decrease)

No definition available.

Name:	fti_BillingsinExcessofCostCurrentIncreaseDecrease
Namespace Prefix:	fti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Billings in Excess of Cost, Current, Increase (Decrease), Percent

+ References

No definition available.

+ Details

Name:	fti_BillingsinExcessofCostCurrentIncreaseDecreasePercent
Namespace Prefix:	fti_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Costs in Excess of Billings (Billings in Excess of Cost), Current, Net

+ References

No definition available.

+ Details

Name:	fti_CostsinExcessofBillingsBillingsinExcessofCostCurrentNet
Namespace Prefix:	fti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Costs in Excess of Billings (Billings in Excess of Cost), Current, Net, Increase (Decrease)

+ References

No definition available.

+ Details

Name:	fti_CostsinExcessofBillingsBillingsinExcessofCostCurrentNetIncreaseDecrease
Namespace Prefix:	fti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Costs in Excess of Billings (Billings in Excess of Cost), Current, Net, Increase (Decrease), Percent

+ References

No definition available.

+ Details

Name:	fti_CostsinExcessofBillingsBillingsinExcessofCostCurrentNetIncreaseDecreasePercent
Namespace Prefix:	fti_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Costs in Excess of Billings, Current, Increase (Decrease)

+ References

No definition available.

+ Details

Name:	fti_CostsinExcessofBillingsCurrentIncreaseDecrease
Namespace Prefix:	fti_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Costs in Excess of Billings, Current, Increase (Decrease), Percent

+ References

No definition available.

+ Details

Name:	fti_CostsinExcessofBillingsCurrentIncreaseDecreasePercent
Namespace Prefix:	fti_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Liability attributable to (i) billings in excess of costs under the percentage of completion contract accounting method representing the difference between contractually invoiced amounts (billings) and revenue recognized based, for example, on costs incurred to estimated total costs at period end or (ii) contractually invoiced amounts (billings) in excess of costs incurred and accumulated under the completed contract accounting method that are expected to be realized within one year or one operating cycle, whichever is longer, from the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57788-111642

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57807-111642

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57795-111642

+ Details

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

- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84173487&loc=SL51747714-108306

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130549-203045

+ Details

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

- Definition

Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings which is expected to be collected within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57795-111642

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57807-111642

+ Details

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

- Definition

Amount of revenue recognized that was previously reported as deferred or unearned revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a).Q1 Response))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

+ Details

Name:	us-gaap_DeferredRevenueRevenueRecognized1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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