Major Customers And Segment Information (Property And Equipment Based Upon The Assets' Physical Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net property and equipment	$ 1,555,668	$ 1,583,625	$ 1,502,673
UNITED STATES
Segment Reporting Information [Line Items]
Net property and equipment	1,185,917	1,181,586	1,120,765
Africa Primarily West Africa [Member]
Segment Reporting Information [Line Items]
Net property and equipment	75,772	73,406	82,495
Europe Primarily North Sea [Member]
Segment Reporting Information [Line Items]
Net property and equipment	83,767	72,544	75,382
Middle East and Asia [Member]
Segment Reporting Information [Line Items]
Net property and equipment	99,974	129,476	84,598
Brazil, Mexico Central And South America [Member]
Segment Reporting Information [Line Items]
Net property and equipment	$ 110,238	$ 126,613	$ 139,433