Properties, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Properties, Plant and Equipment
Gross Investment at Cost	$ 344,485	$ 336,077	$ 340,277
Net Investment	177,712	182,186	188,396
Additions at Cost	14,364	17,623	28,002
Depreciation Expense	19,349	19,457	21,037
United States
Properties, Plant and Equipment
Gross Investment at Cost	112,998	111,987	122,550
Net Investment	51,409	52,541	56,791
Additions at Cost	6,120	5,158	7,639
Depreciation Expense	6,957	7,860	9,862
International
Properties, Plant and Equipment
Gross Investment at Cost	231,487	224,090	217,727
Net Investment	126,303	129,645	131,605
Additions at Cost	8,244	12,465	20,363
Depreciation Expense	12,392	11,597	11,175
Upstream
Properties, Plant and Equipment
Gross Investment at Cost	308,813	298,486	302,243
Net Investment	161,913	165,212	170,584
Additions at Cost	12,929	16,516	26,579
Depreciation Expense	17,623	17,823	19,348
Upstream \| United States
Properties, Plant and Equipment
Gross Investment at Cost	84,602	83,929	93,848
Net Investment	38,722	39,710	43,125
Additions at Cost	4,995	4,432	6,586
Depreciation Expense	5,527	6,576	8,545
Upstream \| International
Properties, Plant and Equipment
Gross Investment at Cost	224,211	214,557	208,395
Net Investment	123,191	125,502	127,459
Additions at Cost	7,934	12,084	19,993
Depreciation Expense	12,096	11,247	10,803
Downstream
Properties, Plant and Equipment
Gross Investment at Cost	30,692	32,145	32,379
Net Investment	13,420	14,290	14,897
Additions at Cost	1,213	903	1,061
Depreciation Expense	1,035	1,288	1,233
Downstream \| United States
Properties, Plant and Equipment
Gross Investment at Cost	23,598	22,795	23,202
Net Investment	10,346	10,196	10,807
Additions at Cost	907	528	696
Depreciation Expense	753	956	878
Downstream \| International
Properties, Plant and Equipment
Gross Investment at Cost	7,094	9,350	9,177
Net Investment	3,074	4,094	4,090
Additions at Cost	306	375	365
Depreciation Expense	282	332	355
All Other
Properties, Plant and Equipment
Gross Investment at Cost	4,980	5,446	5,655
Net Investment	2,379	2,684	2,915
Additions at Cost	222	204	362
Depreciation Expense	691	346	456
All Other \| United States
Properties, Plant and Equipment
Gross Investment at Cost	4,798	5,263	5,500
Net Investment	2,341	2,635	2,859
Additions at Cost	218	198	357
Depreciation Expense	677	328	439
All Other \| International
Properties, Plant and Equipment
Gross Investment at Cost	182	183	155
Net Investment	38	49	56
Additions at Cost	4	6	5
Depreciation Expense	$ 14	$ 18	$ 17

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.13)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(13))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(14))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(8))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_NonUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_UpstreamEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_DownstreamEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: