Business Segment Information (Geographic Segment Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenue	$ 1,427.3	$ 1,545.0	$ 1,695.2	$ 1,695.2	$ 2,156.2	$ 1,976.7	$ 1,985.3	$ 1,824.4	$ 6,362.7	$ 7,942.6	$ 7,126.2
Total Long-lived Assets	1,371.5				1,458.4				1,371.5	1,458.4
United States
Segment Reporting Information [Line Items]
Revenue									1,721.5	2,245.3	1,940.4
Total Long-lived Assets	501.6				490.5				501.6	490.5
Norway
Segment Reporting Information [Line Items]
Revenue									492.1	1,023.3	1,217.7
Total Long-lived Assets	242.4				250.8				242.4	250.8
Brazil
Segment Reporting Information [Line Items]
Revenue									516.9	831.6	689.0
Total Long-lived Assets	116.5				169.1				116.5	169.1
Nigeria
Segment Reporting Information [Line Items]
Revenue									622.1	627.0	335.0
Angola
Segment Reporting Information [Line Items]
Revenue									485.1	406.7	516.0
United Kingdom
Segment Reporting Information [Line Items]
Total Long-lived Assets	93.9				147.0				93.9	147.0
Malaysia
Segment Reporting Information [Line Items]
Total Long-lived Assets	118.5				112.6				118.5	112.6
All other countries
Segment Reporting Information [Line Items]
Revenue									2,525.0	2,808.7	$ 2,428.1
Total Long-lived Assets	$ 298.6				$ 288.4				$ 298.6	$ 288.4