Business Segments (Segment Operating Capital Employed And Segment Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting Information
Total assets	$ 26,660.0	$ 28,263.7
Operating segments
Segment Reporting Information
Total assets	19,574.0	19,978.2
Operating segments | Subsea
Segment Reporting Information
Total assets	12,980.7	12,944.4
Operating segments | Onshore/Offshore
Segment Reporting Information
Total assets	3,878.6	4,604.8
Operating segments | Surface Technologies
Segment Reporting Information
Total assets	2,725.7	2,453.3
Intercompany eliminations
Segment Reporting Information
Total assets	(11.0)	(24.3)
Corporate
Segment Reporting Information
Total assets	$ 7,086.0	$ 8,285.5