Fair Value Measurements - Quantitative Information about Nonrecurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) - Fair Value, Nonrecurring $ in Millions	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	$ 838	$ 165
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
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	581
Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	150	52
Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	150	52
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		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	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	$ 150	$ 52
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	0.01	0.11
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	0.54	0.47
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	0.28	0.31