Basis Of Presentation and Significant Accounting Policies Restatement (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues	$ 2,913.0	$ 3,125.2
Costs and Expenses	2,778.2	2,885.9
Net income attributable to TechnipFMC plc	$ 20.9	$ 95.1
Basic (usd per share)	$ 0.05	$ 0.20
Diluted (usd per share)	$ 0.05	$ 0.20
Basic (in shares)	450.1	464.3
Diluted (in shares)	453.3	465.7
Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 3,125.2
Costs and Expenses		2,885.9
Net income attributable to TechnipFMC plc		$ 95.1
Basic (usd per share)		$ 0.20
Diluted (usd per share)		$ 0.20
Basic (in shares)		464.3
Diluted (in shares)		465.7
Services
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 2,051.1	$ 2,274.0
Cost of goods and services sold	1,644.2	1,826.9
Services | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue		2,427.4
Cost of goods and services sold		1,952.5
Services | Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	(153.4)
Cost of goods and services sold	(125.6)
Products
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	799.3	801.8
Cost of goods and services sold	721.7	660.4
Products | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue		648.4
Cost of goods and services sold		$ 534.8
Products | Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	153.4
Cost of goods and services sold	$ 125.6