Restructuring Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2016	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 59	$ 280	$ 232	$ 331
Asset Impairment Charges	$ 436
Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					331
Restructuring and Related Cost, Incurred Cost			240
Payments for Restructuring			198		106
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs					172
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs					159
2016 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			280
2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			196
Restructuring and Related Cost, Incurred Cost			196
Payments for Restructuring			147
2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			84
Asset Impairment Charges			40
Restructuring and Related Cost, Incurred Cost			44
Payments for Restructuring			18
2016 Plan [Member] | Other Restructuring excluding write-downs [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			44
2015 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				232
2015 Plan [Member] | Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				58	58
2015 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				58
Severance Costs				149	58
2015 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs				83	0
Asset Impairment Charges				64
Restructuring and Related Cost, Incurred Cost				19
2014 Plan [Member] | Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					273
2014 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs					114
2014 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					24
Other Restructuring Costs					159
2014 Plan [Member] | Impaired Assets to be Disposed of by Method Other than Sale, Asset Name [Domain]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges					$ 135
YEMEN | 2015 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges				26
Other Countries [Member] | 2015 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Asset Impairment Charges				$ 38
Operating Segments [Member] | Drilling Rigs [Member] | 2016 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 7