Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Technip Energies	Cumulative Effect, Period of Adoption, Adjustment	Ordinary Shares	Capital in Excess of Par Value of Ordinary Shares	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning balance at Dec. 31, 2019	$ 7,688.1		$ (7.8)	$ 447.1	$ 10,182.8	$ (1,563.1)	$ (7.8)	$ (1,407.5)	$ 28.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to TechnipFMC plc	(3,244.4)					(3,244.4)
Net income (loss)	(3,230.4)								14.0
Other comprehensive income (loss)	(246.2)							(238.3)	(7.9)
Issuance of ordinary shares	(5.4)			2.2	(7.6)
Cash dividends declared	(59.2)					(59.2)
Share-based compensation (Note 15)	38.4				38.4
Other	(1.9)					(1.5)			(0.4)
Ending balance at Jun. 30, 2020	4,175.6			449.3	10,213.6	(4,876.0)		(1,645.8)	34.5
Beginning balance at Mar. 31, 2020	4,084.8			448.3	10,196.8	(4,887.0)		(1,701.7)	28.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to TechnipFMC plc	11.7					11.7
Net income (loss)	15.3								3.6
Other comprehensive income (loss)	59.1							55.9	3.2
Issuance of ordinary shares	1.0			1.0
Share-based compensation (Note 15)	16.8				16.8
Other	(1.4)					(0.7)			(0.7)
Ending balance at Jun. 30, 2020	4,175.6			449.3	10,213.6	(4,876.0)		(1,645.8)	34.5
Beginning balance at Dec. 31, 2020	4,214.3			449.5	10,242.4	(4,915.2)		(1,622.5)	60.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to TechnipFMC plc	201.2					201.2
Net income (loss)	207.0								5.8
Other comprehensive income (loss)	56.5							56.6	(0.1)
Issuance of ordinary shares	1.1			1.1
Share-based compensation (Note 15)	10.7				10.7
Spin-off of Technip Energies (Note 2)		$ (857.3)			(1,108.4)			271.0	(19.9)
Other	(3.0)								(3.0)
Ending balance at Jun. 30, 2021	3,629.3			450.6	9,144.7	(4,714.0)		(1,294.9)	42.9
Beginning balance at Mar. 31, 2021	3,695.5			449.8	9,152.1	(4,547.0)		(1,400.8)	41.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to TechnipFMC plc	(167.0)					(167.0)
Net income (loss)	(164.9)								2.1
Other comprehensive income (loss)	93.4							93.6	(0.2)
Issuance of ordinary shares	0.8			0.8
Share-based compensation (Note 15)	7.3				7.3
Spin-off of Technip Energies (Note 2)		$ (2.4)			(14.7)			12.3
Other	(0.4)								(0.4)
Ending balance at Jun. 30, 2021	$ 3,629.3			$ 450.6	$ 9,144.7	$ (4,714.0)		$ (1,294.9)	$ 42.9