Revenue from Contracts with Customers (Schedule of Revenue from Contracts with Customers Disaggregated by Business Segment) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net		$ 216	$ 231
Protection products revenue		47	49
Transaction processing revenue		44	46
Other income subject to ASC 606		28	28
Loan fee income		119	104
Gains on equity investments		36	0
Total other income not subject to ASC 606		155	104
Total other income by operating segment		490	458
Customer rewards included in discount and interchange revenue		478	446
Deposit product fees reported in net interest income and excluded from other income subject to ASC 606		1	1
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	216	231
Protection products revenue		47	49
Transaction processing revenue		44	46
Other income subject to ASC 606		28	28
Total other income subject to ASC 606	[2]	335	354
Operating Segments [Member] | Direct Banking [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		119	104
Gains on equity investments		0
Total other income not subject to ASC 606		119	104
Total other income by operating segment		366	372
Operating Segments [Member] | Direct Banking [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	197	217
Protection products revenue		47	49
Transaction processing revenue		0	0
Other income subject to ASC 606		3	2
Total other income subject to ASC 606	[2]	247	268
Operating Segments [Member] | Payment Services [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		0	0
Gains on equity investments		36
Total other income not subject to ASC 606		36	0
Total other income by operating segment		124	86
Operating Segments [Member] | Payment Services [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	19	14
Protection products revenue		0	0
Transaction processing revenue		44	46
Other income subject to ASC 606		25	26
Total other income subject to ASC 606	[2]	$ 88	$ 86

[1] Net of rewards, including Cashback Bonus rewards, of $478 million and $446 million for the three months ended March 31, 2020 and 2019, respectively.

[2] Excludes $1 million of deposit product fees that are reported within net interest income for the three months ended March 31, 2020 and 2019.