Fair Value Measurements - Reconciliation of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Balance, beginning of period	$ 1,685	$ 1,673
Included in earnings	(2)	(67)
Purchases/originations	11	30
Settlements	11	24
Transfers into Level 3	2	4
Balance, end of period	1,707	1,664
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	11	(56)
Derivative assets	2,777		$ 2,677
Derivative liabilities	3,223		$ 2,999
Unrealized gains or losses included in other comprehensive income for instruments still held	0	0
Interest rate contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Derivative assets	6	11
Derivative liabilities	6	8
Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Balance, beginning of period	1,737	1,746
Included in earnings	8	(53)
Purchases/originations	11	32
Settlements	0	0
Transfers into Level 3	0	0
Balance, end of period	1,756	1,725
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	25	(35)
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Balance, beginning of period	0	(1)
Included in earnings	9	14
Purchases/originations	0	(2)
Settlements	(9)	(8)
Transfers into Level 3	0	0
Balance, end of period	0	3
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	5	7
Equity Derivatives
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Balance, beginning of period	(168)	(195)
Included in earnings	(17)	(31)
Purchases/originations	0	0
Settlements	23	34
Transfers into Level 3	0	0
Balance, end of period	(162)	(192)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	(17)	(31)
Residential Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Balance, beginning of period	116	123
Included in earnings	(2)	3
Purchases/originations	0	0
Settlements	(3)	(2)
Transfers into Level 3	2	4
Balance, end of period	113	128
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	$ (2)	$ 3