Fair Value Disclosures - Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value, beginning balance	$ 363	$ 337
Realized and Unrealized Gains (Losses),Assets	(10)	(6)
Purchases, Assets	15	397
Sales and Maturities, Assets	(30)	(17)
Issuances and other Settlements, Assets	0	0
Transfers into Level 3, Assets	0	3
Transfers out of Level 3, Assets	0	(3)
Assets measured at fair value, ending balance	338	711
Total Net Unrealized Gains (Losses) Included in Earnings	(10)	(6)
Liabilities measured at fair value, beginning balance	4,431
Realized and Unrealized Gains (Losses), Liabilities	(96)
Purchases, Liabilities	0
Sales and Maturities, Liabilities	0
Issuances and other Settlements, Liabilities	(35)
Transfers into Level 3, Liabilities	0
Transfers out of Level 3, Liabilities	0
Liabilities measured at fair value, ending balance	4,492
Total Net Unrealized Gains (Losses) Included in Earnings	(96)
Other Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value, beginning balance	149	120
Assets measured at fair value, ending balance	152	138
Other Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities measured at fair value, beginning balance	129	279
Liabilities measured at fair value, ending balance	102	258
Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value, beginning balance	214	217
Realized and Unrealized Gains (Losses),Assets	(13)	1
Purchases, Assets	15	372
Sales and Maturities, Assets	(30)	(17)
Issuances and other Settlements, Assets	0	0
Transfers into Level 3, Assets	0	3
Transfers out of Level 3, Assets	0	(3)
Assets measured at fair value, ending balance	186	573
Total Net Unrealized Gains (Losses) Included in Earnings	(13)	1
Contingent Consideration Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities measured at fair value, beginning balance	4,302
Realized and Unrealized Gains (Losses), Liabilities	(99)
Purchases, Liabilities	0
Sales and Maturities, Liabilities	0
Issuances and other Settlements, Liabilities	(11)
Transfers into Level 3, Liabilities	0
Transfers out of Level 3, Liabilities	0
Liabilities measured at fair value, ending balance	4,390
Total Net Unrealized Gains (Losses) Included in Earnings	$ (99)
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Business Combination, Contingent Consideration, Liability, Current
Debt securities [Member] | Trading [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value, beginning balance	$ 79	42
Realized and Unrealized Gains (Losses),Assets	(2)	(1)
Purchases, Assets	4	7
Sales and Maturities, Assets	(2)	0
Issuances and other Settlements, Assets	0	0
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Assets measured at fair value, ending balance	79	48
Total Net Unrealized Gains (Losses) Included in Earnings	$ (2)	$ (1)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)	Nonoperating Income (Expense)
Consolidated Variable Interest Entities [Member] | Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value, beginning balance	$ 135	$ 175
Realized and Unrealized Gains (Losses),Assets	(11)	2
Purchases, Assets	11	365
Sales and Maturities, Assets	(28)	(17)
Issuances and other Settlements, Assets	0	0
Transfers into Level 3, Assets	0	3
Transfers out of Level 3, Assets	0	(3)
Assets measured at fair value, ending balance	107	525
Total Net Unrealized Gains (Losses) Included in Earnings	(11)	2
Other Assets One [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized and Unrealized Gains (Losses),Assets	3	(7)
Purchases, Assets	0	25
Sales and Maturities, Assets	0	0
Issuances and other Settlements, Assets	0	0
Transfers into Level 3, Assets	0	0
Transfers out of Level 3, Assets	0	0
Total Net Unrealized Gains (Losses) Included in Earnings	3	(7)
Other Liabilities One [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized and Unrealized Gains (Losses), Liabilities	3	6
Purchases, Liabilities	0	0
Sales and Maturities, Liabilities	0	0
Issuances and other Settlements, Liabilities	(24)	(15)
Transfers into Level 3, Liabilities	0	0
Transfers out of Level 3, Liabilities	0	0
Total Net Unrealized Gains (Losses) Included in Earnings	$ 3	$ 6
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)	Nonoperating Income (Expense)