Fair Value Measurements - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
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
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
Unfunded commitments, equity securities measured at net asset value	$ 23		$ 23		$ 25
Revaluation period			90 days
Deferred fees	3		$ 3		3
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers into Level 3	35	$ 112	36	$ 367
Transfers Out of Level 3	206	0	634	89
Assets Transfers out of Level 3	(19)	0	(17)	43
Assets, Transfers Into Level 3	0	(9)	0	19
Level 3 | Equity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivatives, net, Transfers out of Level 3	(7)	0	(5)	43
Derivatives, net, Transfers into Level 3	0	(7)	0	22
Unfunded Loan Commitment
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Deferred fees	161		161		$ 158
Domestic deposits | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers into Level 3	0	81	0	130
Transfers Out of Level 3	6	0	31	3
Long-term debt | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers into Level 3	35	31	36	237
Transfers Out of Level 3	$ 200	$ 0	$ 603	$ 86