Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income	Net income
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income	Net income
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income	Net income
Derivatives liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, ending balance	$ (236)	$ (430)	$ (236)	$ (430)
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	68	106	(83)	145
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	53	(250)	179	(366)
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(2)	(1)	(1)	(4)
Assets, Purchases	2	0	3	0
Assets, Issuances	0	1	0	2
Assets, Settlements	(25)	(46)	(4)	(38)
Assets, Transfers Into Level 3	0	(9)	0	19
Assets Transfers out of Level 3	(19)	0	(17)	43
Total assets, ending balance	77	(199)	77	(199)
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	50	(254)	145	(337)
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(2)	(1)	(1)	(4)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(2,665)	(2,564)	(3,012)	(2,388)
Total Realized/Unrealized Gains (Losses) Included in Earnings	(89)	283	(261)	398
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	(22)	14	4	17
Purchases	0	0	0	0
Issuances	(187)	(358)	(376)	(658)
Settlements	260	144	515	316
Transfers Into Level 3	(35)	(112)	(36)	(367)
Transfers Out of Level 3	206	0	634	89
Total liabilities, ending balance	(2,532)	(2,593)	(2,532)	(2,593)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(50)	272	(156)	357
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(22)	14	4	17
Level 3 | Interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(4)	(1)	(5)	0
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	(1)	(1)	0	(1)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Derivatives, net, Purchases	0	0	0	0
Derivatives, net, Issuances	0	0	0	0
Derivatives, net, Settlements	0	0	0	0
Derivatives, net, Transfers into Level 3	0	(2)	0	(3)
Derivatives, net, Transfers out of Level 3	0	0	0	0
Derivatives, net, Ending Balance	(5)	(4)	(5)	(4)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(1)	0	0	(1)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	0	0
Level 3 | Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	0	(1)	0	(2)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	1	0	2
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Derivatives, net, Purchases	0	0	0	0
Derivatives, net, Issuances	0	0	0	0
Derivatives, net, Settlements	0	0	0	0
Derivatives, net, Transfers into Level 3	0	0	0	0
Derivatives, net, Transfers out of Level 3	0	0	0	0
Derivatives, net, Ending Balance	0	0	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	0	0
Level 3 | Equity contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(84)	(1)	(226)	46
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	61	(221)	189	(341)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Derivatives, net, Purchases	0	0	0	0
Derivatives, net, Issuances	0	0	0	0
Derivatives, net, Settlements	5	(53)	17	(52)
Derivatives, net, Transfers into Level 3	0	(7)	0	22
Derivatives, net, Transfers out of Level 3	(7)	0	(5)	43
Derivatives, net, Ending Balance	(25)	(282)	(25)	(282)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	51	(255)	146	(339)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	0	0
Level 3 | Credit contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	2	(2)	2	(2)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	1	0	1
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Derivatives, net, Purchases	0	0	0	0
Derivatives, net, Issuances	0	0	0	0
Derivatives, net, Settlements	0	0	0	0
Derivatives, net, Transfers into Level 3	0	0	0	0
Derivatives, net, Transfers out of Level 3	0	0	0	0
Derivatives, net, Ending Balance	2	(1)	2	(1)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	1	0	1
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	0	0
Level 3 | Other Contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(24)	(24)	(33)	(33)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	(7)	(30)	(9)	(31)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Derivatives, net, Purchases	0	0	0	0
Derivatives, net, Issuances	0	0	0	0
Derivatives, net, Settlements	7	7	18	17
Derivatives, net, Transfers into Level 3	0	0	0	0
Derivatives, net, Transfers out of Level 3	0	0	0	0
Derivatives, net, Ending Balance	(24)	(47)	(24)	(47)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	$ 0	$ 0
Asset-backed securities available-for-sale
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other comprehensive income (loss), net of tax	Other comprehensive income (loss), net of tax
Asset-backed securities available-for-sale | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	107	114	$ 108	$ 120
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(2)	(1)	(1)	(4)
Assets, Purchases	0	0	0	0
Assets, Issuances	0	0	0	0
Assets, Settlements	0	0	(2)	(3)
Assets, Transfers Into Level 3	0	0	0	0
Assets Transfers out of Level 3	0	0	0	0
Total assets, ending balance	105	113	105	113
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0	0	0
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(2)	(1)	$ (1)	$ (4)
Mortgage servicing rights
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other income (loss)	Other income (loss)
Mortgage servicing rights | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	21	21	$ 22	$ 16
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	0	(1)	4
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Assets, Purchases	0	0	0	0
Assets, Issuances	0	1	0	2
Assets, Settlements	0	0	0	0
Assets, Transfers Into Level 3	0	0	0	0
Assets Transfers out of Level 3	0	0	0	0
Total assets, ending balance	21	22	21	22
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0	(1)	2
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0	0	0
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, ending balance	184	96	184	96
Domestic deposits | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(270)	(492)	(373)	(535)
Total Realized/Unrealized Gains (Losses) Included in Earnings	5	24	(1)	45
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	(3)	3	1	1
Purchases	0	0	0	0
Issuances	(2)	0	(2)	0
Settlements	23	46	103	116
Transfers Into Level 3	0	(81)	0	(130)
Transfers Out of Level 3	6	0	31	3
Total liabilities, ending balance	(241)	(500)	(241)	(500)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	5	20	3	38
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(3)	3	1	1
Long-term debt | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(2,395)	(2,072)	(2,639)	(1,853)
Total Realized/Unrealized Gains (Losses) Included in Earnings	(94)	259	(260)	353
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	(19)	11	3	16
Purchases	0	0	0	0
Issuances	(185)	(358)	(374)	(658)
Settlements	237	98	412	200
Transfers Into Level 3	(35)	(31)	(36)	(237)
Transfers Out of Level 3	200	0	603	86
Total liabilities, ending balance	(2,291)	(2,093)	(2,291)	(2,093)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(55)	252	(159)	319
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(19)	$ 11	3	$ 16
Loans held for sale | Loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	50		49
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	0		0
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0		0
Assets, Purchases	2		3
Assets, Issuances	0		0
Assets, Settlements	(37)		(37)
Assets, Transfers Into Level 3	0		0
Assets Transfers out of Level 3	(12)		(12)
Total assets, ending balance	3		3
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0		0
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	$ 0		$ 0