Loans Held-for-Investment - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 33	$ 35
Allowance for loan losses	131	154	$ 241	$ 252
Interest income on nonaccrual loans using cash basis method	1	1
Loans 90 days past due and still accruing interest	0	0
Other liabilities	$ 1,367	1,080
Maximum period for payment deferrals, forbearance and extensions as a response to COVID-19	18 months
Number of loans modified in previous 12 months that have defaulted | loan	0
Loans held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	$ 7,800	9,900
Unfunded Commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other liabilities	$ 14	$ 16