v3.26.1
Loans and Allowance for Loan Losses - Narrative (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Total loans $ 85,197,000,000   $ 39,154,000,000  
Land held for future development, period (in year) 1 year      
Financing receivable, allowance for credit loss $ 942,000,000 $ 417,000,000 442,000,000 $ 414,000,000
Reserve for unfunded commitments 72,000,000   16,000,000  
All financing receivable, allowance for credit loss $ 1,000,000,000.0   458,000,000  
Increase (decrease) in allowance for credit loss     $ 557,000,000  
ACL to loans ratio (as percent) 1.19%   1.17%  
Allowance for credit loss, reasonable and supportable forecast period (in year) 2 years      
Allowance for credit loss, straight-line basis historical period (in year) 1 year      
Allowance for credit loss, measurement input, estimated peak weighted average unemployment rate (in percent) 5.10%   4.60%  
Financing receivable, modified, subsequent default $ 0 $ 0    
Commitments to land additional funds to TDRs $ 0   $ 0  
Substandard        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Retail loan substandard period (in days) 90 days      
Loss        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Retail loan charge off (in days) 120 days      
Asset Pledged as Collateral        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Total loans $ 33,300,000,000   $ 15,700,000,000