Fair Value of Assets and Liabilities - Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income
Level 3
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (23)	$ (14)	$ (23)
Acquired			0
Total net gains (losses) included in net income	(23)	(19)	(1)
Purchases	0	0	0
Sales	0	0	0
Settlements	19	10	10
Repayments	0
Net transfers into (out of) Level 3	0	0	0
Ending balance	(27)	(23)	(14)
Net unrealized gains (losses) included in net income	(23)	(19)	(1)
Trading securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		0	1
Acquired			0
Total net gains (losses) included in net income			(1)
Purchases			0
Sales			0
Settlements			0
Net transfers into (out of) Level 3			0
Ending balance			0
Net unrealized gains (losses) included in net income			0
Interest-only strips | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	38	32	19
Acquired			0
Total net gains (losses) included in net income	(7)	3	(6)
Purchases	0	0	6
Sales	(76)	(68)	(11)
Settlements	0	0	0
Repayments	0
Net transfers into (out of) Level 3	70	71	24
Ending balance	25	38	32
Net unrealized gains (losses) included in net income	(2)	(2)	(4)
Loans held for sale | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	28	12	14
Acquired			0
Total net gains (losses) included in net income	0	1	1
Purchases	2	10	0
Sales	(12)	(18)	0
Settlements	(2)	(3)	(3)
Repayments	(1)
Net transfers into (out of) Level 3	7	26	0
Ending balance	22	28	12
Net unrealized gains (losses) included in net income	0	1	1
Loans held for investment | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	16	0
Acquired			14
Total net gains (losses) included in net income		0	0
Purchases		0	0
Sales		0	(4)
Settlements		(2)	(3)
Net transfers into (out of) Level 3		(14)	9
Ending balance		0	16
Net unrealized gains (losses) included in net income		$ 0	$ 0