Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments - Loan Sales- and Securitization-Related Indemnifications (Details) - Loans sold with recourse - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Loans sold with recourse
Unpaid principal balance of loans sold with recourse	$ 1,019	$ 1,169
Carrying value of related liability for recourse obligations	$ 30	$ 38