Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	$ (2)	$ (14)
Consumer loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	1	(1)
Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	2	(1)
Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	(2)	3
Leases [Member]
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	(3)	$ (15)
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	485		$ 480
Fair Value, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	103		106
Fair Value, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	382		374
Fair Value, Nonrecurring | Consumer loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	103		106
Fair Value, Nonrecurring | Consumer loans | Level 1
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Consumer loans | Level 2
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	103		106
Fair Value, Nonrecurring | Consumer loans | Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | 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		0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 1
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 2
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	382		374
Fair Value, Nonrecurring | Commercial Loans | Level 1
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Commercial Loans | Level 2
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Commercial Loans | Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	382		374
Fair Value, Nonrecurring | Leases [Member]
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Leases [Member] | Level 1
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Leases [Member] | Level 2
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0
Fair Value, Nonrecurring | Leases [Member] | Level 3
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	$ 0		$ 0