Fair Value of Assets and Liabilities - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net  derivative liabilities
Beginning balance	$ (18)	$ (34)	$ (23)	$ (27)
Total net gains (losses) included in net income	(15)	0	(15)	(15)
Purchases			0	0
Sales	0	0	0	0
Settlements	1	8	6	16
Net transfers into (out of) Level 3	0	0	0	0
Ending balance	(32)	(26)	(32)	(26)
Net unrealized gains (losses) included in net income	(15)	0	(15)	(15)
Interest-only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	16	36	13	25
Total net gains (losses) included in net income	(1)	(4)	(3)	(10)
Purchases			0	0
Sales	(5)	(30)	(15)	(38)
Settlements	0	0	0	0
Net transfers into (out of) Level 3	7	21	22	46
Ending balance	17	23	17	23
Net unrealized gains (losses) included in net income	0	(2)	(1)	(4)
Loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	15	22	26	22
Total net gains (losses) included in net income	1	0	1	0
Purchases			2	2
Sales	0	0	(13)	(2)
Settlements	(1)	(1)	(2)	(1)
Net transfers into (out of) Level 3	1	0	2	0
Ending balance	16	21	16	21
Net unrealized gains (losses) included in net income	$ 1	$ 0	$ 1	$ 0