Finance Receivables - Modified as TDR - Non Performing Finance Receivables (Details) - Personal Loan $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($) account	Dec. 31, 2019 USD ($) account	Dec. 31, 2018 USD ($) account
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDR net finance receivables \| $	$ 105	$ 96	$ 64
Number of TDR accounts \| account	15,229	14,732	9,719

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration