Restructuring Charges (Restructuring Charges) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	$ 77	$ 41
2016 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	77
2016 Plan [Member] | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	10
2016 Plan [Member] | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	63
2016 Plan [Member] | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	4
2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	72
2016 Plan [Member] | Employee Severance [Member] | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	10
2016 Plan [Member] | Employee Severance [Member] | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	58
2016 Plan [Member] | Employee Severance [Member] | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	4
2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	5
2016 Plan [Member] | Other Restructuring [Member] | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	0
2016 Plan [Member] | Other Restructuring [Member] | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	5
2016 Plan [Member] | Other Restructuring [Member] | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	0
2015 Plan
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		41
2015 Plan | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		3
2015 Plan | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		33
2015 Plan | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		5
2015 Plan | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		40
2015 Plan | Employee Severance [Member] | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		3
2015 Plan | Employee Severance [Member] | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		32
2015 Plan | Employee Severance [Member] | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		5
2015 Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		1
2015 Plan | Other Restructuring [Member] | Corporate and Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		0
2015 Plan | Other Restructuring [Member] | Core Regional Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		1
2015 Plan | Other Restructuring [Member] | Land Drilling Rigs [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		0
North America [Member] | 2016 Plan [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	24
North America [Member] | 2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	19
North America [Member] | 2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	5
North America [Member] | 2015 Plan | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		8
North America [Member] | 2015 Plan | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		8
North America [Member] | 2015 Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		0
Middle East, North Africa, and Asia [Member] | 2016 Plan [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	9
Middle East, North Africa, and Asia [Member] | 2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	9
Middle East, North Africa, and Asia [Member] | 2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	0
Middle East, North Africa, and Asia [Member] | 2015 Plan | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		6
Middle East, North Africa, and Asia [Member] | 2015 Plan | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		5
Middle East, North Africa, and Asia [Member] | 2015 Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		1
Europe, Sub-Sahara Africa, Russia [Member] | 2016 Plan [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	15
Europe, Sub-Sahara Africa, Russia [Member] | 2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	15
Europe, Sub-Sahara Africa, Russia [Member] | 2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	0
Europe, Sub-Sahara Africa, Russia [Member] | 2015 Plan | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		7
Europe, Sub-Sahara Africa, Russia [Member] | 2015 Plan | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		7
Europe, Sub-Sahara Africa, Russia [Member] | 2015 Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		0
Latin America [Member] | 2016 Plan [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	15
Latin America [Member] | 2016 Plan [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	15
Latin America [Member] | 2016 Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges	$ 0
Latin America [Member] | 2015 Plan | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		12
Latin America [Member] | 2015 Plan | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		12
Latin America [Member] | 2015 Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance, asset impairment and other restructuring charges		$ 0