Income And Other Taxes (Remaining Tax Years Subject To Examination By Major Tax Jurisdiction) (Details)	12 Months Ended
	Dec. 31, 2018
Abu Dhabi [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Abu Dhabi [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Angola [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2017
Angola [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Australia [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2008
Australia [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Belgium [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2016
Belgium [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Canada [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2000
Canada [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Equatorial Guinea [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2007
Equatorial Guinea [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Indonesia [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2007
Indonesia [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Iraq [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2013
Iraq [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Malaysia [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2009
Malaysia [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Nigeria [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2006
Nigeria [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Norway [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2007
Norway [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Papua New Guinea [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2008
Papua New Guinea [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
Russia [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2016
Russia [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
United Kingdom [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2015
United Kingdom [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018
United States [Member] | Earliest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2006
United States [Member] | Latest Tax Year [Member]
Income and Other Taxes [Line Items]
Open tax years by major tax jurisdiction	2018