Fair Value of Assets and Liabilities - Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net  derivative liabilities
Beginning balance	$ (23)	$ (27)
Total net gains (losses) included in net income	0	0
Purchases	0	0
Sales	0	0
Settlements	3	6
Net transfers into (out of) Level 3	0	0
Ending balance	(20)	(21)
Net unrealized gains (losses) included in net income	0	0
Interest-only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	13	25
Total net gains (losses) included in net income	(1)	(3)
Purchases	0	0
Sales	(2)	(3)
Settlements	0	0
Net transfers into (out of) Level 3	9	9
Ending balance	19	28
Net unrealized gains (losses) included in net income	(1)	(1)
Loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	26	22
Total net gains (losses) included in net income	0	0
Purchases	1	1
Sales	(13)	(2)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Ending balance	14	21
Net unrealized gains (losses) included in net income	$ 0	$ 0