Revenue - Disaggregation of Revenue, Geographical (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Lease and other revenue	$ 60.7	$ 55.1	$ 163.4	$ 144.7
Total revenue	3,143.8	4,140.9	9,229.9	11,373.9
Services
Disaggregation of Revenue [Line Items]
Revenue	2,487.9	3,374.9	7,159.2	9,301.0
Products
Disaggregation of Revenue [Line Items]
Revenue	595.2	710.9	1,907.3	1,928.2
Subsea
Disaggregation of Revenue [Line Items]
Revenue	1,178.3		3,516.7
Lease and other revenue	30.8		90.0
Total revenue	1,209.1	1,478.2	3,606.7	4,585.2
Subsea | Services
Disaggregation of Revenue [Line Items]
Revenue	885.2		2,525.9
Subsea | Products
Disaggregation of Revenue [Line Items]
Revenue	293.1		990.8
Subsea | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	421.4		1,136.3
Subsea | America
Disaggregation of Revenue [Line Items]
Revenue	437.4		1,219.3
Subsea | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	118.2		368.1
Subsea | Africa
Disaggregation of Revenue [Line Items]
Revenue	162.5		703.9
Subsea | Middle East
Disaggregation of Revenue [Line Items]
Revenue	38.8		89.1
Onshore/Offshore
Disaggregation of Revenue [Line Items]
Revenue	1,532.5		4,448.3
Total revenue	1,532.5	2,308.1	4,448.3	5,885.0
Onshore/Offshore | Services
Disaggregation of Revenue [Line Items]
Revenue	1,532.5		4,448.3
Onshore/Offshore | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	831.5		2,537.9
Onshore/Offshore | America
Disaggregation of Revenue [Line Items]
Revenue	89.4		253.0
Onshore/Offshore | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	300.6		906.5
Onshore/Offshore | Africa
Disaggregation of Revenue [Line Items]
Revenue	54.8		202.3
Onshore/Offshore | Middle East
Disaggregation of Revenue [Line Items]
Revenue	256.2		548.6
Surface Technologies
Disaggregation of Revenue [Line Items]
Revenue	372.3		1,101.5
Lease and other revenue	29.9		73.4
Total revenue	402.2	$ 353.9	1,174.9	$ 902.3
Surface Technologies | Services
Disaggregation of Revenue [Line Items]
Revenue	70.2		185.0
Surface Technologies | Products
Disaggregation of Revenue [Line Items]
Revenue	302.1		916.5
Surface Technologies | Europe, Russia, Central Asia
Disaggregation of Revenue [Line Items]
Revenue	66.0		172.5
Surface Technologies | America
Disaggregation of Revenue [Line Items]
Revenue	208.3		653.3
Surface Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	34.1		85.9
Surface Technologies | Africa
Disaggregation of Revenue [Line Items]
Revenue	16.3		43.4
Surface Technologies | Middle East
Disaggregation of Revenue [Line Items]
Revenue	$ 47.6		$ 146.4