Revenue from Contracts with Customers (Schedule of Revenue from Contracts with Customers Disaggregated by Business Segment) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net		$ 238	$ 255	$ 691	$ 785
Protection products revenue		44	48	135	146
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		17	23	59	73
Loan fee income		100	120	304	326
Gains on equity investments		0	0	79	0
Total other income not subject to ASC 606		100	120	383	326
Total other income by operating segment		449	498	1,411	1,476
Customer rewards included in discount and interchange revenue		514	520	1,400	1,400
Deposit product fees reported in net interest income and excluded from other income subject to ASC 606		1		2	2
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	238	255	691	785
Protection products revenue		44	48	135	146
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		17	23	59	73
Total other income subject to ASC 606	[2]	349	378	1,028	1,150
Operating Segments [Member] | Direct Banking [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		100	120	304	326
Gains on equity investments				0
Total other income not subject to ASC 606		100	120	304	326
Total other income by operating segment		371	409	1,091	1,217
Operating Segments [Member] | Direct Banking [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	225	238	644	738
Protection products revenue		44	48	135	146
Transaction processing revenue		0	0	0	0
Other income subject to ASC 606		2	3	8	7
Total other income subject to ASC 606	[2]	271	289	787	891
Operating Segments [Member] | Payment Services [Member]
Disaggregation of Revenue [Line Items]
Loan fee income		0	0	0	0
Gains on equity investments				79
Total other income not subject to ASC 606		0	0	79	0
Total other income by operating segment		78	89	320	259
Operating Segments [Member] | Payment Services [Member] | Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Discount and interchange revenue, net	[1]	13	17	47	47
Protection products revenue		0	0	0	0
Transaction processing revenue		50	52	143	146
Other income subject to ASC 606		15	20	51	66
Total other income subject to ASC 606	[2]	$ 78	$ 89	$ 241	$ 259

[1] Net of rewards, including Cashback Bonus rewards, of $514 million and $520 million for the three months ended September 30, 2020 and 2019, respectively.

[2] Excludes $1 million of deposit product fees that are reported within net interest income for the three months ended September 30, 2020. Deposit product fees were immaterial for the three months ended September 30, 2019.