Business Segments (Segment Assets) (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Assets		$ 24,784.5	$ 28,263.7
Operating segments
Segment Reporting Information [Line Items]
Total Assets		18,192.2	19,978.2
Operating segments | Subsea
Segment Reporting Information [Line Items]
Total Assets		11,037.8	12,944.4
Operating segments | Onshore/Offshore
Segment Reporting Information [Line Items]
Total Assets		4,355.2	4,604.8
Operating segments | Surface Technologies
Segment Reporting Information [Line Items]
Total Assets		2,825.6	2,453.3
Intercompany eliminations
Segment Reporting Information [Line Items]
Total Assets		(26.4)	(24.3)
Corporate
Segment Reporting Information [Line Items]
Total Assets	[1]	$ 6,592.3	$ 8,285.5

[1] Corporate includes cash, LIFO adjustments, deferred income tax balances, legal provisions, property, plant and equipment not associated with a specific segment, pension assets and the fair value of derivative financial instruments.