Loans Held-for-Investment - Narrative (Details) loans in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) loans	Dec. 31, 2020 USD ($) loans	Dec. 31, 2019 USD ($) loans	Jan. 01, 2020 USD ($)	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest on loans held-for-investment	$ 35	$ 43
Allowance for loan losses	154	252	$ 107	$ 130	$ 128
Interest income that would have been accrued	1	1	$ 1
Loans 90 days or greater past due and still accruing	$ 0	$ 0
Loans modified in the preceding 12 months that subsequently defaulted | loans	0	0	0
Other liabilities	$ 880	$ 1,272
Maximum period for payment deferrals, forbearance and extensions as response to COVID-19	18 months
Reserve for unfunded commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other liabilities	$ 16	28		$ 10
Loans held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	$ 9,900	$ 11,600