Loan Receivables (Schedule of Loans That Entered a Modification Program During the Period) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) accounts	Dec. 31, 2018 USD ($) accounts	Dec. 31, 2017 USD ($) accounts
Credit Card Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Accounts that entered a loan modification program during the period, number of accounts | accounts	368,009	268,817	133,139
Accounts that entered a loan modification program during the period, balances | $	$ 2,364	$ 1,713	$ 776
Total Other Loans [Member] | Personal Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Accounts that entered a loan modification program during the period, number of accounts | accounts	10,945	8,260	6,567
Accounts that entered a loan modification program during the period, balances | $	$ 147	$ 111	$ 82
Total Other Loans [Member] | Private Student Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Accounts that entered a loan modification program during the period, number of accounts | accounts	6,742	4,057	3,942
Accounts that entered a loan modification program during the period, balances | $	$ 124	$ 74	$ 69