Business Segments (Segment Operating Capital Employed And Segment Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information
Total assets	$ 27,058.5	$ 28,263.7
Operating segments
Segment Reporting Information
Total assets	20,923.6	19,978.2
Operating segments | Subsea
Segment Reporting Information
Total assets	13,837.8	12,944.4
Operating segments | Onshore/Offshore
Segment Reporting Information
Total assets	4,458.8	4,604.8
Operating segments | Surface Technologies
Segment Reporting Information
Total assets	2,647.2	2,453.3
Intercompany eliminations
Segment Reporting Information
Total assets	(20.2)	(24.3)
Corporate
Segment Reporting Information
Total assets	$ 6,134.9	$ 8,285.5