Earnings Per Share (Reconciliation Of Number Of Shares Used For Basic And Diluted Earnings Per Share ("EPS") Calculation ) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share
Net income (loss) attributable to TechnipFMC plc	$ (3,256.1)	$ 20.9
Weighted average number of shares outstanding (in shares)	447.5	450.1
Total shares and dilutive securities (in shares)	447.5	453.3
Basic earnings per share attributable to TechnipFMC plc (usd per share)	$ (7.28)	$ 0.05
Diluted earnings per share attributable to technipFMC plc (usd per share)	$ (7.28)	$ 0.05
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Dilutive effect of share-based payment arrangements (in shares)		1.0
Performance Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share
Dilutive effect of share-based payment arrangements (in shares)		2.2