v3.26.1
Investments in Limited Partnerships - Additional Information (Detail)
$ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Partnership
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Schedule of Investments [Line Items]          
Unfunded equity commitments in other liabilities $ 23,687,232   $ 23,687,232   $ 23,664,420
Tax benefits including low-income housing and historic tax credits 24,846 $ 13,558 47,635 $ 12,886  
Partnerships losses and impairment $ 3,100 $ 3,000 $ 6,100 $ 4,900  
Number of limited partnerships held | Partnership     3    
Investment Program, Proportional Amortization Method, Applied, Amortization Expense, Statement of Cash Flows [Extensible Enumeration] Tax benefits including low-income housing and historic tax credits Tax benefits including low-income housing and historic tax credits Tax benefits including low-income housing and historic tax credits Tax benefits including low-income housing and historic tax credits  
Equity Method Investments [Member]          
Schedule of Investments [Line Items]          
Tax benefits including low-income housing and historic tax credits     $ 11,600   9,900
Limited Liability Company [Member]          
Schedule of Investments [Line Items]          
Amount invested in partnerships $ 4,200   4,200   4,000
Variable Interest Entity, Not Primary Beneficiary [Member]          
Schedule of Investments [Line Items]          
Unfunded equity commitments in other liabilities 31,400   31,400   37,500
Variable Interest Entity, Not Primary Beneficiary [Member] | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssets          
Schedule of Investments [Line Items]          
Amount invested in partnerships $ 83,600   $ 83,600   $ 83,700