The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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Legal Proceedings - 10-K (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
Legal Proceedings - 10-K (Details) - USD ($) $ in Millions	Aug. 04, 2020	Sep. 30, 2018	Dec. 31, 2019	Jul. 31, 2019	Nov. 30, 2015	Apr. 30, 2015	Mar. 31, 2015
Loss Contingencies [Line Items]
Document Period End Date	Aug. 04, 2020
Legal Reserve \| Maximum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued			$ 100.0
Interchange Litigation
Loss Contingencies [Line Items]
Litigation Settlement Amount		$ 900.0	6,600.0
Payments for Legal Settlements		5,300.0	$ 700.0
Conditional Return of Legal Settlements Paid Maximum Amount		$ 700.0
Litigation Settlement, Trigger Percent of Opt Out by Class Members for Return of Portion of Settlement Payments		15.00%	15.00%
Interchange Litigation \| Visa
Loss Contingencies [Line Items]
Litigation Settlement Amount		$ 600.0
Payments for Legal Settlements			$ 467.0
Conditional Return of Legal Settlements Paid Maximum Amount		$ 467.0
Jo Ann Howard Pc Et Al V Cassity Et Al
Loss Contingencies [Line Items]
Alleged Present And Future Losses			600.0
Compensatory damages							$ 356.0
Punitive damages							$ 36.0
Prejudgement interests						$ 179.0
Reduced Compensatory Damages					$ 289.0
Jo Ann Howard Pc Et Al V Cassity Et Al \| Pending Litigation
Loss Contingencies [Line Items]
Compensatory damages				$ 72.0
Punitive damages				15.0
Loss contingency, damages awarded, interest, value				$ 15.0
Increase (decrease) in damages awarded			2.6
Loss contingency, damages awarded, value			99.5
Loss contingency, damages sought, value			$ 7.0