Revenue Disaggregation of Revenue, Geographical (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Contract with Customer, Performance Obligation Satisfied in Previous Period									$ 470.8		$ 1,176.5
Lease Income									142.0		266.5		$ 222.7
Total revenue	$ 3,426.1	$ 3,335.7	$ 3,158.5	$ 3,130.3	$ 3,726.8	$ 3,335.1	$ 3,434.2	$ 2,913.0	13,050.6		13,409.1		12,552.9
Service [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									9,708.2		9,789.7		9,057.6
Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									3,200.4		3,352.9		3,272.6
Subsea [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									5,416.5		5,407.0		4,721.8
Lease Income									54.9	[1]	116.0	[1]	118.2
Total revenue									5,471.4		5,523.0		4,840.0
Subsea [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									3,121.1		3,244.5		2,687.1
Subsea [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									2,295.4		2,162.5		2,034.7
Subsea [Member] | Europe, Russia, Central Asia [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									1,641.9		1,745.2		1,528.1
Subsea [Member] | Americas [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									1,957.7		1,770.0		1,721.5
Subsea [Member] | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									753.2		659.9		532.9
Subsea [Member] | Africa [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									893.9		824.8		758.1
Subsea [Member] | Middle East [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									169.8		407.1		181.2
Surface Technologies [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									972.1		1,466.8		1,487.7
Lease Income									87.1	[1]	150.5	[1]	104.5
Total revenue									1,059.2		1,617.3		1,592.2
Surface Technologies [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									150.2		276.4		249.8
Surface Technologies [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									821.9		1,190.4		1,237.9
Surface Technologies [Member] | Europe, Russia, Central Asia [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									188.2		236.7		227.7
Surface Technologies [Member] | Americas [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									373.1		732.1		865.5
Surface Technologies [Member] | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									123.4		189.3		123.2
Surface Technologies [Member] | Africa [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									45.8		61.1		57.9
Surface Technologies [Member] | Middle East [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									241.6		247.6		213.4
Technip Energies
Disaggregation of Revenue [Line Items]
Product and service revenue									6,520.0		6,268.8		6,120.7
Lease Income									0.0	[1]	0.0	[1]	0.0
Total revenue									6,520.0		6,268.8		6,120.7
Technip Energies | Service [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									6,436.9		6,268.8		6,120.7
Technip Energies | Product [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									83.1		0.0		0.0
Technip Energies | Europe, Russia, Central Asia [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									3,111.6		2,813.1		3,506.1
Technip Energies | Americas [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									982.6		766.2		365.1
Technip Energies | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									1,094.3		1,152.5		1,236.1
Technip Energies | Africa [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									884.4		526.0		252.7
Technip Energies | Middle East [Member]
Disaggregation of Revenue [Line Items]
Product and service revenue									$ 447.1		$ 1,011.0		$ 760.7

[1] Represents revenue not subject to ASC Topic 606.