Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Unfunded commitments, equity securities measured at net asset value	$ 29		$ 29
Revaluation period	90 days
Deferred fees	$ 4		4
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	89	$ 16
Fair Value Liability, Transfers Into Level 3	255	2
Level 3 | Equity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivatives, net, Transfers out of Level 3	43	(1)
Derivatives, net, Transfers into Level 3	29	0
Unfunded Loan Commitment
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Deferred fees	155		$ 151
Deposits | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	3	15
Fair Value Liability, Transfers Into Level 3	49	0
Fixed rate long-term debt | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	86	1
Fair Value Liability, Transfers Into Level 3	$ 206	$ 2