Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	$ (16)	$ (15)	$ (15)	$ (7)
Consumer loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	(3)	(1)	(11)	(1)
Consumer loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	1	2	4	8
Commercial loans held for sale
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	(13)	0	(10)	(12)
Commercial Loans
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	3	(12)	3	57
Leases
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total Gains (Losses)	(4)	$ (4)	(1)	$ (59)
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	395		395		$ 2,202
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		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	252		252		201
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	143		143		2,001
Fair Value, Nonrecurring | 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	14		14		1,766
Fair Value, Nonrecurring | Consumer 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		0
Fair Value, Nonrecurring | Consumer 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	5		5		24
Fair Value, Nonrecurring | Consumer 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	9		9		1,742
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	115		115		102
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		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	115		115		102
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		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	132		132		143
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		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	132		132		75
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		68
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	134		134		186
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		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		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	134		134		186
Fair Value, Nonrecurring | Leases
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Total assets at fair value on a non-recurring basis	0		0		5
Properties held for sale					5
Fair Value, Nonrecurring | Leases | 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		0
Fair Value, Nonrecurring | Leases | 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		0
Fair Value, Nonrecurring | Leases | 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		$ 5