Fair Value of Financial Instruments (Realized And Unrealized Gains And Losses Included In Earnings Pertaining To Level 3 Assets And Liabilities) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 4	$ (13)
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (25)	$ (3)
Other net realized gains (losses)	0	(15)
Fair Value Inputs Level 3 [Member] | Total Gains (Losses) Included in Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(4)	(3)
Total revenues	(28)	(14)
Fair Value Inputs Level 3 [Member] | Change in Unrealized Gains (Losses) for the Period Included in Earnings for Assets and Liabilities still held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(4)	(3)
Total revenues	(3)	(3)
Fair Value Inputs Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Total Gains (Losses) Included in Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(24)	3
Other net realized gains (losses)	0	(14)
Fair Value Inputs Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Change in Unrealized Gains (Losses) for the Period Included in Earnings for Assets and Liabilities still held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	1	0
Other net realized gains (losses)	$ 0	$ 0