Fair Value Measurements - Fair Values of Assets and Liabilities (Significant Unobservable Level 3 Inputs Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	$ 2,472	$ 2,677
Derivative liabilities	(2,798)	(2,999)
Residential mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Residential mortgage loans	$ 108	$ 116
Residential mortgage loans | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Interest rate risk factor	(51.90%)	(23.40%)
Credit risk factor	0.00%	0.00%
Residential mortgage loans | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Interest rate risk factor	4.60%	3.40%
Credit risk factor	0.50%	0.60%
Residential mortgage loans | Weighted-Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Interest rate risk factor	(13.30%)	(11.60%)
Credit risk factor	0.20%	0.20%
Servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Servicing rights	$ 1,704	$ 1,737
Servicing rights | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepayment speed	0.00%	0.00%
OAS (bps)	0.0420	0.0477
Servicing rights | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepayment speed	100.00%	100.00%
OAS (bps)	0.1823	0.1447
Servicing rights | Fixed | Weighted-Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepayment speed	5.80%	5.90%
OAS (bps)	0.0459	0.0569
Servicing rights | Adjustable | Weighted-Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepayment speed	16.90%	20.30%
OAS (bps)	0.0731	0.1016
IRLCs, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	$ 2	$ 5
IRLCs, net | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Loan closing rates	20.80%	20.90%
IRLCs, net | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Loan closing rates	96.00%	96.00%
IRLCs, net | Weighted-Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Loan closing rates	83.50%	82.30%
Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities	$ (170)	$ (168)
Swap | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Timing of the resolution of the Covered Litigation	Jun. 30, 2027	Dec. 31, 2024
Swap | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Timing of the resolution of the Covered Litigation	Mar. 31, 2028	Mar. 31, 2027
Swap | Weighted-Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Timing of the resolution of the Covered Litigation	Dec. 31, 2027	Dec. 31, 2025