Income Taxes (Details 4) $ in Millions	Dec. 31, 2017 USD ($)
Deemed Repatriation Tax Payments Due By Year [Line Items]
2018	$ 0
2019-2020	122
2021-2022	116
2023 and Thereafter	491
Total	$ 729

Represents estimated obligation under the tax act to pay deemed repatriation tax on certain non US earnings.

No definition available.

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Namespace Prefix:	aexc_
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Represents estimated obligation under the tax act to pay deemed repatriation tax on certain non US earnings.

No definition available.

Name:	aexc_Deemedrepatriationtaxpaymentsduebyyear20192020rmember
Namespace Prefix:	aexc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents estimated obligation under the tax act to pay deemed repatriation tax on certain non US earnings.

No definition available.

Name:	aexc_Deemedrepatriationtaxpaymentsduebyyear20212022member
Namespace Prefix:	aexc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents estimated obligation under the tax act to pay deemed repatriation tax on certain non US earnings.

No definition available.

Name:	aexc_Deemedrepatriationtaxpaymentsduebyyear2023andthereaftermember
Namespace Prefix:	aexc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	aexc_DeemedrepatriationtaxpaymentsduebyyearLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents estimated obligation under the tax act to pay deemed repatriation tax on certain non US earnings payable to AXP.

No definition available.

Name:	aexc_Deemedrepatriationtaxpaymentsduebyyeartotalmember
Namespace Prefix:	aexc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant