Basis of Presentation (Details Textuals) - USD ($) $ in Millions	Jan. 01, 2019	Sep. 30, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Right-of-use asset obtained in exchange for operating lease liability	$ 700
Minimum [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses net increase, Card Member loans and receivables (as a percentage)		25.00%
Minimum [Member] | Card Member Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses net increase, Card Member loans and receivables (as a percentage)		55.00%
Maximum [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses net increase, Card Member loans and receivables (as a percentage)		40.00%
Maximum [Member] | Card Member Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses net increase, Card Member loans and receivables (as a percentage)		70.00%