STOCKHOLDERS’ EQUITY - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 4,214.3	$ 7,688.1	$ 10,388.9
Reclassification adjustment for net (gains) losses included in net income, net of tax	0.0	0.0	(12.0)
Other comprehensive income (loss), net of tax	84.8	(214.4)	(48.5)
Spin-off of Technip Energies	(897.2)
Ending balance	3,418.4	4,214.3	7,688.1
Foreign Currency Translation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,401.2)	(1,230.1)
Other comprehensive income (loss) before reclassifications, net of tax	29.2	(171.1)
Reclassification adjustment for net (gains) losses included in net income, net of tax		0.0
Other comprehensive income (loss), net of tax	29.2	(171.1)
Spin-off of Technip Energies	213.6
Ending balance	(1,158.4)	(1,401.2)	(1,230.1)
Hedging
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	34.0	(5.8)
Other comprehensive income (loss) before reclassifications, net of tax	(19.8)	26.8
Reclassification adjustment for net (gains) losses included in net income, net of tax	(11.8)	13.0
Other comprehensive income (loss), net of tax	(31.6)	39.8
Spin-off of Technip Energies	(19.7)
Ending balance	(17.3)	34.0	(5.8)
Defined Pension  and Other Post-Retirement Benefits
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(255.3)	(171.6)
Other comprehensive income (loss) before reclassifications, net of tax	70.8	(92.9)
Reclassification adjustment for net (gains) losses included in net income, net of tax	18.0	9.2
Other comprehensive income (loss), net of tax	88.8	(83.7)
Spin-off of Technip Energies	37.2
Ending balance	(129.3)	(255.3)	(171.6)
Accumulated Other Comprehensive  Loss Attributable to TechnipFMC plc
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,622.5)	(1,407.5)
Other comprehensive income (loss) before reclassifications, net of tax	80.2	(237.2)
Reclassification adjustment for net (gains) losses included in net income, net of tax	6.2	22.2
Other comprehensive income (loss), net of tax	86.4	(215.0)
Spin-off of Technip Energies	231.1
Ending balance	(1,305.0)	(1,622.5)	(1,407.5)
Accumulated Other Comprehensive  Loss Attributable to Non-Controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(4.1)	(4.7)
Other comprehensive income (loss) before reclassifications, net of tax	(1.6)	0.6
Reclassification adjustment for net (gains) losses included in net income, net of tax	0.0	0.0
Other comprehensive income (loss), net of tax	(1.6)	0.6
Spin-off of Technip Energies	0.0
Ending balance	$ (5.7)	$ (4.1)	$ (4.7)