Debt - Narrative (Details) - USD ($)	3 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt instrument, face amount	$ 22,000,000,000	$ 19,100,000,000
Secured Debt [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	3,172,000,000.000
Revolving Credit Facility [Member] \| Unsecured Debt [Member] \| International Segment [Member]
Debt Instrument [Line Items]
Increase in Credit Facilities during period	66,000,000
Revolving Credit Facility [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Increase in Credit Facilities during period	366,000,000
Senior Notes [Member] \| Parent Company [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	2,750,000,000.00
Senior Notes [Member] \| Parent Company [Member] \| Four Point Two Percent Senior Notes Due March Twenty Twenty-One [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 1,500,000,000.0
Interest rate (percent)	4.20%
Senior Notes [Member] \| Parent Company [Member] \| Five Point Two Five Percent Senior Notes Due March Twenty Twenty-Six [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 1,250,000,000.00
Interest rate (percent)	5.25%

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	acf_LongtermandShorttermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=acf_InternationalSegmentMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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- Details

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