Loans - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income that was recorded on nonaccrual loans and included in interest income during the period	$ 0	$ 0	$ 0
Loans, net	$ 59,894	$ 62,753
Executive Officers and Directors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans executive officers and directors as a percentage of total equity (less than)	5.00%	5.00%
90+ Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	$ 229	$ 313
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans modified	0	0	0
Loans, net	20,550	21,702
Consumer loans | 90+ Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	108	112
Consumer loans | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral-dependent loans	256	282
Loans, net	19,789	21,035
Consumer loans | Residential mortgages | 90+ Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	100	105
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral-dependent loans	513	524
Loans modified	353	438	616
Additional commitments for loans modified	116	25
Loans, net	39,344	41,051
Commercial loans | 90+ Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans modified, subsequently default	14	30	$ 166
Loans, net	$ 121	$ 201