Credit Card and Student Loan Securitization Activities (Narrative) (Details) - Variable Interest Entity, Primary Beneficiary [Member]	3 Months Ended
Mar. 31, 2020 classes trust
Student Loan Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Number of trusts issuing securities	1
Number of trusts	2
Discover Card Execution Note Trust [Member] \| Credit Card Securitization Trusts [Member]
Variable Interest Entity [Line Items]
Number of classes of securities in debt structure (in classes) \| classes	4

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.

No definition available.

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