Loan Receivables (Schedule of Delinquent and Non-Accruing Loans) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		$ 2,218		$ 2,312
Loan receivables, 90 or more days delinquent and accruing		1,013		1,014
Loan receivables, total non-accruing		273		266
30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		1,123		1,214
90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		1,095		1,098
Credit Card Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		1,935		2,019
Loan receivables, 90 or more days delinquent and accruing		940		940
Loan receivables, total non-accruing	[1]	238		237
Estimated gross interest income that would have been recorded based on original terms		10	$ 12
Credit Card Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		919		999
Credit Card Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		1,016		1,020
Total Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		283		293
Loan receivables, 90 or more days delinquent and accruing		73		74
Loan receivables, total non-accruing		35		29
Total Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		204		215
Total Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		79		78
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	174		181
Loan receivables, 90 or more days delinquent and accruing	[2]	46		45
Loan receivables, total non-accruing	[2]	15		11
Total Other Loans [Member] | Private Student Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	126		136
Total Other Loans [Member] | Private Student Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due	[2]	48		45
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		100		105
Loan receivables, 90 or more days delinquent and accruing		27		29
Loan receivables, total non-accruing		12		12
Total Other Loans [Member] | Personal Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		71		74
Total Other Loans [Member] | Personal Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		29		31
Total Other Loans [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		9		7
Loan receivables, 90 or more days delinquent and accruing		0		0
Loan receivables, total non-accruing		8		6
Total Other Loans [Member] | Other Loans [Member] | 30-89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		7		5
Total Other Loans [Member] | Other Loans [Member] | 90 or More Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Loan receivables, past due		$ 2		$ 2

[1] The Company estimates that the gross interest income that would have been recorded in accordance with the original terms of non-accruing credit card loans was $10 million and $12 million for the three months ended March 31, 2020 and 2019, respectively. The Company does not separately track the amount of gross interest income that would have been recorded in accordance with the original terms of loans. This amount was estimated based on customers' current balances and most recent interest rates.

[2] Includes PCD loans for all periods presented.