Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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-Name Accounting Standards Codification
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-SubTopic 210
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Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Asset Securitizations (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Securitized Trusts [Line Items]
Restricted cash included in Other assets per Consolidated Balance Sheets	$ 363.0	$ 336.0	$ 286.0
American Express Charge Trust [Member]
Securitized Trusts [Line Items]
Restricted cash included in Other assets per Consolidated Balance Sheets	3.0	7.1
American Express Lending Trust [Member]
Securitized Trusts [Line Items]
Restricted cash included in Other assets per Consolidated Balance Sheets	67.0	55.0
Restricted cash held by trusts [Member]
Securitized Trusts [Line Items]
Restricted cash included in Other assets per Consolidated Balance Sheets	$ 70.4	$ 62.1