Fair Value Measurements - Quantitative Information about Nonrecurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) - Fair Value, Nonrecurring $ in Millions	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	$ 2,202	$ 658
Consumer loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	1,766	4
Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	143	68
Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	186	270
Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	2,001	273
Level 3 | Consumer loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	1,742	0
Level 3 | Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	68	0
Level 3 | Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	$ 186	$ 270
Adjusted market price | Level 3 | Consumer loans held for sale | Minimum | Market comparables and internal assumptions
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.10
Adjusted market price | Level 3 | Consumer loans held for sale | Maximum | Market comparables and internal assumptions
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	1
Adjusted market price | Level 3 | Consumer loans held for sale | Weighted Average | Market comparables and internal assumptions
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.98
Adjusted market price | Level 3 | Commercial loans held for sale | Market comparables and internal assumptions
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.94
Loss severity rates | Level 3 | Commercial Loans | Minimum | Valuation of third party appraisal on underlying collateral
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.02	0
Loss severity rates | Level 3 | Commercial Loans | Maximum | Valuation of third party appraisal on underlying collateral
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.76	0.76
Loss severity rates | Level 3 | Commercial Loans | Weighted Average | Valuation of third party appraisal on underlying collateral
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Range of Inputs	0.23	0.35