Related Party Transactions Schedule of Related Party Transactions (Tables) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Trade receivables	$ 123.5		$ 61.7
Trade payables	60.8		148.6
Revenue	139.5	$ 92.5
Expenses	52.7	26.2
TTSJV W.L.L. \| Equity Method Investee
Related Party Transaction [Line Items]
Trade receivables	46.0
Revenue	52.8
TP JGC Coral France SNC \| Equity Method Investee
Related Party Transaction [Line Items]
Trade receivables	45.4		31.6
Revenue	26.7	28.2
Technip Odebrecht PLSV CV \| Equity Method Investee
Related Party Transaction [Line Items]
Trade receivables	12.5		10.9
Anadarko Petroleum Company \| Board of Directors Chairman
Related Party Transaction [Line Items]
Trade receivables	9.6		4.9
Trade payables			0.7
Revenue	44.5	50.3
JGC Corporation
Related Party Transaction [Line Items]
Trade payables	28.8		69.5
Expenses	14.3	15.1
Chiyoda
Related Party Transaction [Line Items]
Trade payables	28.7		70.0
Expenses	14.2	7.7
IFP Energies nouvelles \| Board of Directors Chairman
Related Party Transaction [Line Items]
Trade payables	1.1		2.4
Expenses	1.0	1.1
Magma Global Limited \| Equity Method Investee
Related Party Transaction [Line Items]
Trade payables	0.6		0.6
Expenses	1.9
Dofcon Navegacao \| Equity Method Investee
Related Party Transaction [Line Items]
Trade payables	0.2		2.5
Revenue	4.1	0.0
Serimax Holdings SAS \| Equity Method Investee
Related Party Transaction [Line Items]
Expenses	17.5
Others \| Other Affiliates
Related Party Transaction [Line Items]
Trade receivables	10.0		14.3
Trade payables	1.4		$ 2.9
Revenue	11.4	14.0
Expenses	$ 3.8	$ 2.3

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