Loans Held-for-Investment - Summary of Amortized Cost (Details) - Consumer loans	Mar. 31, 2020 USD ($)
Servicing Asset at Amortized Cost [Line Items]
Amortized cost basis	$ 66
Residential first mortgage loans
Servicing Asset at Amortized Cost [Line Items]
Amortized cost basis	44
Home equity
Servicing Asset at Amortized Cost [Line Items]
Amortized cost basis	20
Other
Servicing Asset at Amortized Cost [Line Items]
Amortized cost basis	$ 2