Credit Quality - Summary of Transactions in the ALLL by Portfolio Segment (Parenthetical) (Details) - Other Consumer Loans, Point of Sale - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Losses charged-off	$ 12	$ 8	$ 35	$ 18
Recoveries of losses previously charged- off	$ 12	$ 8	$ 35	$ 18

Amount of writeoff of financing receivable, charged against allowance for credit loss.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Period Type:	duration