Business Segments (Other Business Segment Information) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Capital expenditures	$ 291.8	$ 454.4	$ 368.1
Depreciation and amortization	447.2	509.6	550.4
Research and development expense	119.8	162.9	189.2
Operating segments \| Subsea [Member]
Segment Reporting Information [Line Items]
Capital expenditures	213.6	287.7	223.2
Depreciation and amortization	324.9	345.6	440.4
Research and development expense	66.5	134.4	145.2
Operating segments \| Surface Technologies [Member]
Segment Reporting Information [Line Items]
Capital expenditures	38.5	96.6	111.9
Depreciation and amortization	70.1	107.9	66.6
Research and development expense	8.8	15.3	14.3
Operating segments \| Technip Energies
Segment Reporting Information [Line Items]
Capital expenditures	13.0	22.6	7.6
Depreciation and amortization	34.2	38.7	38.2
Research and development expense	44.5	13.2	29.7
Corporate
Segment Reporting Information [Line Items]
Capital expenditures	26.7	47.5	25.4
Depreciation and amortization	$ 18.0	$ 17.4	$ 5.2

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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