Loans Held-for-Investment - Narrative (Details) $ in Millions	3 Months Ended
	Jun. 30, 2022 USD ($) loan	Dec. 31, 2021 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 41	$ 35
Total loans held-for-investment	14,655	13,408
Allowance for loan losses	122	154	$ 131	$ 202	$ 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	$ 1,163	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
Asset pledged as collateral | Federal Home Loan Bank Advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held-for-investment	$ 8,600	9,900
Unfunded Commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other liabilities	$ 13	$ 16