Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue
Lease Income		$ 142.0	$ 266.5	$ 222.7
Total revenue		13,050.6	13,409.1	12,552.9
Costs and expenses
Leases, Income Statement, Cost		116.7	167.9	143.4
Selling, general and administrative expense		1,066.2	1,228.1	1,140.6
Research and development expense		119.8	162.9	189.2
Restructuring, Settlement and Impairment Provisions		3,501.3	2,490.8	1,831.2
Merger transaction and integration costs			31.2	36.5
Total costs and expenses		15,936.2	14,935.8	13,470.5
Other income (expense), net		31.1	(220.7)	(323.9)
Income from equity affiliates (Note 12)		63.0	62.9	114.3
Loss before interest income, interest expense and income taxes		(2,791.5)	(1,684.5)	(1,127.2)
Interest income		56.6	116.5	121.4
Interest expense		(349.6)	(567.8)	(482.3)
Loss before income taxes	[1]	(3,084.5)	(2,135.8)	(1,488.1)
Provision for income taxes (Note 21)		153.4	276.3	422.7
Net loss		(3,237.9)	(2,412.1)	(1,910.8)
Net profit attributable to non-controlling interests		$ (49.7)	(3.1)	(10.8)
Net loss attributable to TechnipFMC plc			$ (2,415.2)	$ (1,921.6)
Earnings (loss) per share attributable to TechnipFMC plc (Note 8)
Basic earnings (loss) per share (usd per share)		$ (7.33)	$ (5.39)
Diluted earnings (loss) per share (usd per share)		$ (7.33)	$ (5.39)	$ (4.20)
Weighted average shares outstanding (Note 8)
Basic (in shares)		448.7	448.0	458.0
Diluted (in shares)		448.7	448.0	458.0
Separation costs		$ 39.5	$ 72.1	$ 0.0
Service [Member]
Revenue
Revenue		9,708.2	9,789.7	9,057.6
Costs and expenses
Cost of product revenue		8,261.9	7,767.2	7,452.7
Product [Member]
Revenue
Revenue		3,200.4	3,352.9	3,272.6
Costs and expenses
Cost of product revenue		$ 2,830.8	$ 3,015.6	$ 2,676.9

[1] Includes amounts attributable to non-controlling interests.