Business Segment and Geographic Information (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue			$ 23,995	$ 20,620	$ 15,887
Operating income (loss):
Total operating income (loss)			2,467	1,374	(6,770)
Impairments and other charges		$ 265	265	647	3,357	[1]
Impairments and other charges	[1]		(265)	(647)	(3,357)
Interest expense, net of interest income			(554)	(593)	(639)
Other, net			(99)	(99)	(216)
Income (loss) from continuing operations before income taxes			1,814	682	(7,625)
Capital expenditures:
Total capital expenditures			2,026	1,373	798
Depreciation, depletion and amortization:
Total depreciation, depletion and amortization			1,606	1,556	1,503
Total assets:
Total assets			25,982	25,085
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net			8,961	8,521
Completion and Production
Revenue:
Revenue			15,973	13,077	8,882
Operating income (loss):
Total operating income (loss)			2,278	1,625	108
Impairments and other charges					2,100
Capital expenditures:
Total capital expenditures			1,364	1,111	500
Depreciation, depletion and amortization:
Total depreciation, depletion and amortization			1,058	953	900
Total assets:
Total assets	[2]		13,231	12,276
Drilling and Evaluation
Revenue:
Revenue			8,022	7,543	7,005
Operating income (loss):
Total operating income (loss)			745	726	801
Impairments and other charges					1,200
Capital expenditures:
Total capital expenditures			657	261	297
Depreciation, depletion and amortization:
Total depreciation, depletion and amortization			512	563	569
Total assets:
Total assets	[2]		8,037	7,837
Corporate and shared assets
Total assets:
Total assets	[3]		4,714	4,972
Total operations
Operating income (loss):
Total operating income (loss)			3,023	2,351	909
Corporate and other
Operating income (loss):
Total operating income (loss)	[4]		(291)	(330)	(4,322)
Impairments and other charges					10
Capital expenditures:
Total capital expenditures			5	1	1
Depreciation, depletion and amortization:
Total depreciation, depletion and amortization			36	40	34
VENEZUELA
Operating income (loss):
Impairments and other charges	[1]			(647)
North America [Member]
Revenue:
Revenue			14,431	11,564	6,770
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net			5,672	4,922
Latin America [Member]
Revenue:
Revenue			2,065	2,116	1,860
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net			974	945
Europe/Africa/CIS [Member]
Revenue:
Revenue			2,945	2,781	2,993
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net			938	1,098
Middle East/Asia [Member]
Revenue:
Revenue			4,554	4,159	$ 4,264
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net			$ 1,377	$ 1,556

[1] Impairments and other charges are as follows: -For the year ended December 31, 2018, the aggregate charge of $265 million represents a write-down of all of our remaining investment in Venezuela, consisting of receivables, fixed assets, inventory and other assets and liabilities. -For the year ended December 31, 2017, the aggregate charge of $647 million represents a fair market value adjustment on our existing promissory note with our primary customer in Venezuela and a full reserve against our other accounts receivable with this customer. -For the year ended December 31, 2016, the aggregate charge of $3.4 billion consisted of fixed asset impairments and write-offs, inventory write-downs, impairments of intangible assets, severance costs, country and facility closures, and other charges related to the energy downturn. This included $2.1 billion attributable to Completion and Production, $1.2 billion attributable to Drilling and Evaluation and $10 million attributable to Corporate and other.

[2] Assets associated with specific segments primarily include receivables, inventories, certain identified property, plant and equipment (including field service equipment), equity in and advances to related companies and goodwill.

[3] Corporate and other shared assets primarily include cash and equivalents and deferred tax assets.

[4] Includes certain expenses not attributable to a particular business segment, such as costs related to support functions and corporate executives, and also includes amortization expense associated with intangible assets recorded as a result of acquisitions. Also includes merger-related costs and a termination fee during the year ended December 31, 2016.