Loans Held-for-Investment - Changes in ALLL by Class of Loan (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Allowance for Loan Losses [Roll Forward]
Beginning balance	$ 154	$ 252
(Benefit) provision	(2)	(24)
Charge-offs	(23)	(4)
Recoveries	2	17
Ending allowance balance	131	241
Consumer loans | Residential first mortgage loans
Allowance for Loan Losses [Roll Forward]
Beginning balance	40	49
(Benefit) provision	4	(2)
Charge-offs	(1)	(2)
Recoveries	0	0
Ending allowance balance	43	45
Consumer loans | Home equity
Allowance for Loan Losses [Roll Forward]
Beginning balance	14	25
(Benefit) provision	1	(5)
Charge-offs	0	0
Recoveries	1	0
Ending allowance balance	16	20
Consumer loans | Other consumer
Allowance for Loan Losses [Roll Forward]
Beginning balance	36	39
(Benefit) provision	(1)	(6)
Charge-offs	(2)	(1)
Recoveries	1	1
Ending allowance balance	34	33
Commercial loans | Commercial real estate
Allowance for Loan Losses [Roll Forward]
Beginning balance	28	84
(Benefit) provision	(6)	0
Charge-offs	0	0
Recoveries	0	0
Ending allowance balance	22	84
Commercial loans | Commercial and industrial
Allowance for Loan Losses [Roll Forward]
Beginning balance	32	51
(Benefit) provision	1	(11)
Charge-offs	(20)	(1)
Recoveries	0	16
Ending allowance balance	13	55
Commercial loans | Warehouse lending
Allowance for Loan Losses [Roll Forward]
Beginning balance	4	4
(Benefit) provision	(1)	0
Charge-offs	0	0
Recoveries	0	0
Ending allowance balance	$ 3	$ 4