Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Unfunded commitments, equity securities measured at net asset value	$ 29	$ 33
Revaluation period	90 days
Deferred fees	$ 4	3
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	146	85
Assets Transfers out of Level 3	60	2
Fair Value Liability, Transfers Into Level 3	251	1
Assets, Transfers Into Level 3	(27)	3
Level 3 | Equity contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivatives, net, Transfers out of Level 3	84	2
Derivatives, net, Transfers into Level 3	27	37
Unfunded Loan Commitment
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Deferred fees	151	137
Deposits | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	92	63
Fair Value Liability, Transfers Into Level 3	151	0
Fixed rate long-term debt | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Transfers Out of Level 3	54	22
Fair Value Liability, Transfers Into Level 3	100	1
Residential mortgages | Level 3 | Trading assets, excluding derivatives:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets Transfers out of Level 3	(24)	0
Assets, Transfers Into Level 3	0	0
Other | Level 3 | Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets Transfers out of Level 3	0	0
Assets, Transfers Into Level 3	$ 0	$ 28