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, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share
Net income attributable to TechnipFMC plc	$ 20.9	$ 95.1
Weighted average number of shares outstanding (in shares)	450.1	464.3
Total shares and dilutive securities (in shares)	453.3	465.7
Basic earnings per share attributable to TechnipFMC plc (usd per share)	$ 0.05	$ 0.20
Diluted earnings per share attributable to technipFMC plc (usd per share)	$ 0.05	$ 0.20
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Dilutive effect of share-based payment arrangements (in shares)	1.0
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share
Dilutive effect of share-based payment arrangements (in shares)		0.1
Performance Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share
Dilutive effect of share-based payment arrangements (in shares)	2.2	1.3