Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

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

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

- Definition

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

- Details

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

- Definition

Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 45

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=37586315&loc=d3e32123-109318

+ Details

Name:	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	gm_BusinessGroupAxis=gm_AutomotiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	gm_BusinessGroupAxis=gm_GmFinancialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

Goodwill (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2013
Goodwill [Roll Forward]
Goodwill	$ 1,560us-gaap_Goodwill	$ 1,973us-gaap_Goodwill
Impairment charges	(120)us-gaap_GoodwillImpairmentLoss	(541)us-gaap_GoodwillImpairmentLoss	(27,145)us-gaap_GoodwillImpairmentLoss
Goodwill from business combinations		154us-gaap_GoodwillAcquiredDuringPeriod
Effect of foreign currency and other	(13)us-gaap_GoodwillTranslationAdjustments	(26)us-gaap_GoodwillTranslationAdjustments
Goodwill	1,427us-gaap_Goodwill	1,560us-gaap_Goodwill	1,973us-gaap_Goodwill	1,973us-gaap_Goodwill	1,560us-gaap_Goodwill
Accumulated impairment charges	(30,558)	(30,438)	(29,897)	(29,897)	(30,438)
Reversal of Valuation Allowance			(36,364)
Automotive [Member]
Goodwill [Roll Forward]
Goodwill	138	695
Impairment charges	(120)	(541)
Goodwill from business combinations		10
Effect of foreign currency and other	(18)	(26)
Goodwill	0	138			138
Accumulated impairment charges	(30,558)	(30,438)	(29,897)	(29,897)	(30,438)
GM Financial [Member]
Goodwill [Roll Forward]
Goodwill	1,422	1,278
Impairment charges	0	0
Goodwill from business combinations		144
Effect of foreign currency and other	5	0
Goodwill	1,427	1,422			1,422
Accumulated impairment charges	0	0	0	0	0
GMSA [Member] \| Automotive [Member]
Goodwill [Roll Forward]
Impairment charges	(120)
Goodwill	0
GMNA [Member] \| Automotive [Member]
Goodwill [Roll Forward]
Impairment charges				(26,400)
Reversal of Valuation Allowance			36,200
GME [Member] \| Automotive [Member]
Goodwill [Roll Forward]
Impairment charges			(590)
GMIO [Member]
Goodwill [Roll Forward]
Impairment charges					(481)
GMIO [Member] \| Automotive [Member]
Goodwill [Roll Forward]
Impairment charges		(541)	(156)
Goodwill		$ 0			$ 0