Consolidated Statements of Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net income (loss)		$ (3,237.9)	$ (2,412.1)	$ (1,910.8)
Foreign currency translation adjustments
Foreign currency translation adjustments		(169.1)	15.6	(183.3)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	[1]	(169.1)	3.6	(224.4)
Net gains (losses) on hedging instruments
Net gains (losses) arising during the period		25.4	8.9	(58.7)
Reclassification adjustment for net losses (gains) included in net income		13.0	18.2	(2.0)
Net gains (losses) on hedging instruments	[2]	38.4	27.1	(60.7)
Pension and other post-retirement benefits
Net losses arising during the period		(88.3)	(81.5)	(72.4)
Prior service cost arising during the period		(4.6)	(0.7)	(2.1)
Reclassification adjustment for settlement losses (gains) included in net income		1.4	0.2	(2.5)
Reclassification adjustment for amortization of prior service cost included in net income		0.9	2.0	1.2
Reclassification adjustment for amortization of net actuarial loss included in net income		6.9	0.8	0.3
Net pension and other post-retirement benefits	[3]	(83.7)	(79.2)	(75.5)
Other comprehensive loss, net of tax		(214.4)	(48.5)	(360.6)
Comprehensive loss		(3,452.3)	(2,460.6)	(2,271.4)
Comprehensive income attributable to non-controlling interest		(50.4)	(2.4)	(6.2)
Comprehensive loss attributable to TechnipFMC plc		$ (3,502.7)	$ (2,463.0)	$ (2,277.6)

[1] Net of income tax (expense) benefit of nil, $7.9 and $3.6 for the years ended December 31, 2020, 2019 and 2018, respectively.

[2] Net of income tax (expense) benefit of $(9.7), $(6.9) and $16.6 for the years ended December 31, 2020, 2019 and 2018, respectively.

[3] Net of income tax (expense) benefit of $25.5, $20.3 and $15.5 for the years ended December 31, 2020, 2019 and 2018, respectively.