RELATED PARTY TRANSACTIONS - Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Related Party Transaction [Line Items]
Revenue	$ 103.6	$ 4.3
Equinor ASA \| Director
Related Party Transaction [Line Items]
Revenue	95.5	0.0
Technip Energies \| Equity Method Investee
Related Party Transaction [Line Items]
Revenue	1.5	0.0
Techdof Brasil AS \| Equity Method Investee
Related Party Transaction [Line Items]
Revenue	3.5	1.3
Others \| Other Affiliates
Related Party Transaction [Line Items]
Revenue	$ 3.1	$ 3.0

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.1(c))
-URI http://asc.fasb.org/extlink&oid=120401555&loc=SL114874292-224272

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

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