Impairment, Restructuring and Other Expense (Details) employee in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2015 employee	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring and Impairment [Line Items]
Impairment expense		$ 34.3	$ 38.2	$ 45.2
Charges		157.2	304.8	392.9
Restructuring and impairment expense		191.5	343.0	438.1
Restructuring workforce reduction | employee	6
Subsea
Restructuring and Impairment [Line Items]
Impairment expense		11.5	23.0	42.9
Charges		88.4	58.7	34.0
Onshore/Offshore
Restructuring and Impairment [Line Items]
Impairment expense		0.0	14.6	0.0
Charges		27.0	214.4	342.2
Surface Technologies
Restructuring and Impairment [Line Items]
Impairment expense		10.2	0.0	0.0
Charges		9.0	0.0	0.0
Corporate and other
Restructuring and Impairment [Line Items]
Impairment expense		12.6	0.6	2.3
Charges		$ 32.8	$ 31.7	$ 16.7