Business Segments (Geographic Segment Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 3,726.8	$ 3,335.1	$ 3,434.2	$ 2,913.0	$ 3,323.0	$ 3,143.8	$ 2,960.9	$ 3,125.2	$ 13,409.1	$ 12,552.9	$ 15,056.9
Property, Plant and Equipment, Net	3,162.0				3,259.8				3,162.0	3,259.8
Russia
Segment Reporting Information [Line Items]
Revenues									2,378.0	2,773.3	4,894.2
Norway
Segment Reporting Information [Line Items]
Revenues									1,371.1	1,202.6	971.2
Property, Plant and Equipment, Net	333.0				311.4				333.0	311.4
Brazil
Segment Reporting Information [Line Items]
Revenues									1,099.7	1,478.7	911.1
Property, Plant and Equipment, Net	313.2				325.8				313.2	325.8
ISRAEL
Segment Reporting Information [Line Items]
Revenues									757.0	243.8	6.9
UNITED KINGDOM
Segment Reporting Information [Line Items]
Revenues									540.8	442.1	465.9
Property, Plant and Equipment, Net	957.1				925.6				957.1	925.6
UNITED STATES
Segment Reporting Information [Line Items]
Revenues									1,931.2	1,275.8	1,534.7
Property, Plant and Equipment, Net	558.1				589.9				558.1	589.9
INDIA
Segment Reporting Information [Line Items]
Revenues									518.0	214.0	135.2
ANGOLA
Segment Reporting Information [Line Items]
Revenues									447.8	385.7	1,016.2
AUSTRALIA
Segment Reporting Information [Line Items]
Revenues									372.8	926.6	953.9
UNITED ARAB EMIRATES
Segment Reporting Information [Line Items]
Revenues									327.2	460.3	308.5
MALAYSIA
Segment Reporting Information [Line Items]
Revenues									283.8	362.3	374.8
CHINA
Segment Reporting Information [Line Items]
Revenues									272.9	112.3	104.7
INDONESIA
Segment Reporting Information [Line Items]
Revenues									237.6	130.7	295.4
NETHERLANDS
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	493.0				360.5				493.0	360.5
All Other Countries
Segment Reporting Information [Line Items]
Revenues									2,871.2	2,544.7	$ 3,084.2
Property, Plant and Equipment, Net	$ 507.6				$ 746.6				$ 507.6	$ 746.6