Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 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
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	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
Derivatives liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	$ (353)
Total liabilities, ending balance	(217)	$ (353)
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	(83)	145
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	183	(373)
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(1)	(8)
Assets, Purchases	13	0
Assets, Issuances	0	18
Assets, Settlements	9	29
Assets, Transfers Into Level 3	44	42
Assets Transfers out of Level 3	(27)	(64)
Total assets, ending balance	138	(83)
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	129	(233)
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(1)	(8)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(3,012)	(2,388)
Total Realized/Unrealized Gains (Losses) Included in Earnings	(423)	306
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	(1)	10
Purchases	0	0
Issuances	(834)	(1,287)
Settlements	1,167	672
Transfers Into Level 3	(93)	(594)
Transfers Out of Level 3	984	269
Total liabilities, ending balance	(2,212)	(3,012)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(193)	243
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(1)	10
Level 3 | Interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(5)	0
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	1	(2)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0
Derivatives, net, Purchases	0	0
Derivatives, net, Issuances	0	0
Derivatives, net, Settlements	0	0
Derivatives, net, Transfers into Level 3	0	(3)
Derivatives, net, Transfers out of Level 3	0	0
Derivatives, net, Ending Balance	(4)	(5)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	1	(1)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	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	(2)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	2
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0
Derivatives, net, Purchases	0	0
Derivatives, net, Issuances	0	0
Derivatives, net, Settlements	0	0
Derivatives, net, Transfers into Level 3	0	0
Derivatives, net, Transfers out of Level 3	0	0
Derivatives, net, Ending Balance	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0
Level 3 | Equity contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(226)	46
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	226	(340)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0
Derivatives, net, Purchases	0	0
Derivatives, net, Issuances	0	0
Derivatives, net, Settlements	27	(4)
Derivatives, net, Transfers into Level 3	1	8
Derivatives, net, Transfers out of Level 3	(7)	(64)
Derivatives, net, Ending Balance	21	(226)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	130	(233)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	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)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	1	3
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0
Derivatives, net, Purchases	0	0
Derivatives, net, Issuances	0	0
Derivatives, net, Settlements	0	1
Derivatives, net, Transfers into Level 3	(2)	0
Derivatives, net, Transfers out of Level 3	0	0
Derivatives, net, Ending Balance	1	2
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	1	3
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0
Level 3 | Other Contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Derivatives, net, Beginning Balance	(33)	(33)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Earnings	(44)	(36)
Derivatives, net, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	0	0
Derivatives, net, Purchases	0	0
Derivatives, net, Issuances	0	0
Derivatives, net, Settlements	42	36
Derivatives, net, Transfers into Level 3	0	0
Derivatives, net, Transfers out of Level 3	0	0
Derivatives, net, Ending Balance	(35)	(33)
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	0
Derivatives, net, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	$ 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	$ 108	$ 120
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	0	0
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(1)	(8)
Assets, Purchases	0	0
Assets, Issuances	0	0
Assets, Settlements	(3)	(4)
Assets, Transfers Into Level 3	0	0
Assets Transfers out of Level 3	0	0
Total assets, ending balance	104	108
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)	$ (1)	$ (8)
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	$ 22	$ 16
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	(3)	3
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Assets, Purchases	0	0
Assets, Issuances	0	3
Assets, Settlements	0	0
Assets, Transfers Into Level 3	0	0
Assets Transfers out of Level 3	0	0
Total assets, ending balance	19	22
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(3)	1
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	0	0
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	91
Total assets, ending balance	200	91
Domestic deposits | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(373)	(535)
Total Realized/Unrealized Gains (Losses) Included in Earnings	(3)	54
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	3	2
Purchases	0	0
Issuances	(95)	0
Settlements	139	258
Transfers Into Level 3	0	(182)
Transfers Out of Level 3	36	30
Total liabilities, ending balance	(293)	(373)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	4	36
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	3	2
Long-term debt | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total liabilities, beginning balance	(2,639)	(1,853)
Total Realized/Unrealized Gains (Losses) Included in Earnings	(420)	252
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income	(4)	8
Purchases	0	0
Issuances	(739)	(1,287)
Settlements	1,028	414
Transfers Into Level 3	(93)	(412)
Transfers Out of Level 3	948	239
Total liabilities, ending balance	(1,919)	(2,639)
Current Period Unrealized Gains (Losses) Still Held Included in Earnings	(197)	207
Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	(4)	8
Loans held for sale | Loans | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets, beginning balance	49	0
Assets, Total Realized/Unrealized Gains (Losses) Included in Earnings	2	(3)
Assets, Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Assets, Purchases	13	0
Assets, Issuances	0	15
Assets, Settlements	(57)	0
Assets, Transfers Into Level 3	45	37
Assets Transfers out of Level 3	(20)	0
Total assets, ending balance	32	49
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Earnings	0	(3)
Assets, Current Period Unrealized Gains (Losses) Still Held Included in Other Comprehensive Income (Loss)	$ 0	$ 0