Restructuring and Other Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring and Impairment [Line Items]
Asset Impairment Charges	$ 3,287.4	$ 2,484.1	$ 1,792.6
Restructuring and Related Cost, Incurred Cost	112.1	6.7	38.6
COVID-19 expenses	101.8
Restructuring, Settlement and Impairment Provisions	3,501.3	2,490.8	1,831.2
Goodwill, Impairment Loss	3,083.4	1,988.7
Other Asset Impairment Charges	204.0	495.4
Operating lease right-of-use assets
Restructuring and Impairment [Line Items]
Other Asset Impairment Charges	33.6
Subsea [Member]
Restructuring and Impairment [Line Items]
Asset Impairment Charges	2,854.5	1,798.6	1,784.2
Restructuring and Related Cost, Incurred Cost	52.9	(46.4)	17.7
COVID-19 expenses	50.1
Restructuring, Settlement and Impairment Provisions	2,957.5	1,752.2	1,801.9
Goodwill, Impairment Loss	2,747.5	1,321.9	1,383.0
Subsea [Member] | Plant, property and equipment
Restructuring and Impairment [Line Items]
Other Asset Impairment Charges	88.4	153.8	372.9
Technip Energies
Restructuring and Impairment [Line Items]
Asset Impairment Charges	10.3	0.0	0.0
Restructuring and Related Cost, Incurred Cost	39.3	17.0	(3.4)
COVID-19 expenses	44.0
Restructuring, Settlement and Impairment Provisions	93.6	17.0	(3.4)
Goodwill, Impairment Loss	0.0
Surface Technologies [Member]
Restructuring and Impairment [Line Items]
Asset Impairment Charges	419.3	685.5	4.5
Restructuring and Related Cost, Incurred Cost	13.2	18.7	9.3
COVID-19 expenses	7.7
Restructuring, Settlement and Impairment Provisions	440.2	704.2	13.8
Goodwill, Impairment Loss	335.9	666.8
Surface Technologies [Member] | Plant, property and equipment
Restructuring and Impairment [Line Items]
Other Asset Impairment Charges	82.0	168.9
Corporate and Other [Member]
Restructuring and Impairment [Line Items]
Asset Impairment Charges	3.3	0.0	3.9
Restructuring and Related Cost, Incurred Cost	6.7	17.4	15.0
COVID-19 expenses	0.0
Restructuring, Settlement and Impairment Provisions	$ 10.0	$ 17.4	$ 18.9