Summary of Significant Accounting Policies - Narrative (Detail)	12 Months Ended
	Dec. 31, 2025 segment repaymentPeriod state
Property, Plant and Equipment [Line Items]
Number of reportable segments | segment	2
Threshold period past due, nonaccrual	90 days
Maximum threshold period past due to be classified as current	29 days
Number of minimum repayment periods for return to accrual status | repaymentPeriod	6
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Charge for depreciation, range of life	30 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Charge for depreciation, range of life	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Charge for depreciation, range of life	10 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Charge for depreciation, range of life	15 years
Computer Software | Minimum
Property, Plant and Equipment [Line Items]
Software, useful life	3 years
Computer Software | Maximum
Property, Plant and Equipment [Line Items]
Software, useful life	10 years
Wealth Management segment
Property, Plant and Equipment [Line Items]
Services provided by business units, number of states | state	19