Loans Held-for-Investment - UPB of Loan Sales and Purchases in the Loans Held-for-Investment Portfolio (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans sold	$ 92	$ 492	$ 217
Net gain associated with loan sales	0	3	2
Loans purchased	0	63	300
Premium associated with loans purchased	0	0	11
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans purchased	0	0	249
Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans purchased	0	63	51
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans sold	$ 92	$ 492	$ 217