Revenue - Disaggregation of Revenue, Geographical (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Lease revenue	$ 29.8	$ 85.7	$ 105.7	$ 200.9
Total revenue	3,335.7	3,335.1	9,624.5	9,682.3
Services
Disaggregation of Revenue [Line Items]
Revenue	2,479.0	2,409.6	7,101.9	7,009.5
Products
Disaggregation of Revenue [Line Items]
Revenue	826.9	839.8	2,416.9	2,471.9
Subsea
Disaggregation of Revenue [Line Items]
Revenue	1,488.8	1,299.7	4,090.6	3,945.6
Lease revenue	13.0	42.5	42.8	90.6
Subsea | Services
Disaggregation of Revenue [Line Items]
Revenue	865.2	743.8	2,346.9	2,359.6
Subsea | Products
Disaggregation of Revenue [Line Items]
Revenue	623.6	555.9	1,743.7	1,586.0
Subsea | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	478.3	390.8	1,327.9	1,250.0
Subsea | Americas
Disaggregation of Revenue [Line Items]
Revenue	493.5	513.1	1,437.9	1,232.0
Subsea | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	220.6	171.0	543.7	448.4
Subsea | Africa
Disaggregation of Revenue [Line Items]
Revenue	254.2	143.6	637.0	663.2
Subsea | Middle East
Disaggregation of Revenue [Line Items]
Revenue	42.2	81.2	144.1	352.0
Technip Energies
Disaggregation of Revenue [Line Items]
Revenue	1,608.2	1,596.3	4,694.2	4,436.4
Lease revenue	0.0	0.0	0.0	0.0
Technip Energies | Services
Disaggregation of Revenue [Line Items]
Revenue	1,584.6	1,596.3	4,639.3	4,436.4
Technip Energies | Products
Disaggregation of Revenue [Line Items]
Revenue	23.6	0.0	54.9	0.0
Technip Energies | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	821.5	682.4	2,074.6	1,975.2
Technip Energies | Americas
Disaggregation of Revenue [Line Items]
Revenue	199.1	156.9	794.6	514.2
Technip Energies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	255.9	311.7	804.5	889.1
Technip Energies | Africa
Disaggregation of Revenue [Line Items]
Revenue	248.6	158.6	660.5	330.1
Technip Energies | Middle East
Disaggregation of Revenue [Line Items]
Revenue	83.1	286.7	360.0	727.8
Surface Technologies
Disaggregation of Revenue [Line Items]
Revenue	208.9	353.4	734.0	1,099.4
Lease revenue	16.8	43.2	62.9	110.3
Surface Technologies | Services
Disaggregation of Revenue [Line Items]
Revenue	29.2	69.5	115.7	213.5
Surface Technologies | Products
Disaggregation of Revenue [Line Items]
Revenue	179.7	283.9	618.3	885.9
Surface Technologies | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	43.6	55.5	142.2	171.3
Surface Technologies | Americas
Disaggregation of Revenue [Line Items]
Revenue	64.8	171.0	295.2	564.1
Surface Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	25.7	50.3	88.0	139.4
Surface Technologies | Africa
Disaggregation of Revenue [Line Items]
Revenue	10.5	14.9	38.8	41.1
Surface Technologies | Middle East
Disaggregation of Revenue [Line Items]
Revenue	64.3	61.7	169.8	183.5
Operating Segments | Subsea
Disaggregation of Revenue [Line Items]
Total revenue	1,501.8	1,342.2	4,133.4	4,036.2
Operating Segments | Technip Energies
Disaggregation of Revenue [Line Items]
Total revenue	1,608.2	1,596.3	4,694.2	4,436.4
Operating Segments | Surface Technologies
Disaggregation of Revenue [Line Items]
Total revenue	$ 225.7	$ 396.6	$ 796.9	$ 1,209.7