v3.26.1
Business Combination - Narrative (Details)
$ / shares in Units, $ in Millions
3 Months Ended
Jan. 01, 2026
USD ($)
$ / shares
shares
Mar. 31, 2026
USD ($)
$ / shares
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
$ / shares
Business Combination [Line Items]        
Common stock, par value (in dollars per share) | $ / shares   $ 1.00   $ 1.00
Goodwill $ 1,849 $ 3,478   $ 1,849
Merger-related expense   275 $ 0  
Synovus Financial Corp        
Business Combination [Line Items]        
Goodwill 1,629      
Identifiable intangible assets 1,110      
Merger-related expense   275    
Synovus Financial Corp | Advisory Fee        
Business Combination [Line Items]        
Merger-related expense   100    
Synovus Financial Corp | Equity Acceleration Expense        
Business Combination [Line Items]        
Merger-related expense   70    
Synovus Financial Corp | Other Employee-Related Costs        
Business Combination [Line Items]        
Merger-related expense   91    
Synovus Financial Corp | Other Acquisition-Related Costs        
Business Combination [Line Items]        
Merger-related expense   $ 15    
Synovus Financial Corp | CDI        
Business Combination [Line Items]        
Identifiable intangible assets $ 848      
Acquired finite-lived intangible assets, useful life 10 years      
Synovus Financial Corp | Wealth Customer Relationships        
Business Combination [Line Items]        
Identifiable intangible assets $ 262      
Acquired finite-lived intangible assets, useful life 14 years      
Synovus Financial Corp        
Business Combination [Line Items]        
Common stock, par value (in dollars per share) | $ / shares $ 1.00      
Synovus Financial Corp | Synovus Financial Corp        
Business Combination [Line Items]        
Conversion ratio (in shares) | shares 0.5237      
Synovus Financial Corp | Synovus Financial Corp | Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D        
Business Combination [Line Items]        
Business Combination, Conversion Ratio | shares 1      
Synovus Financial Corp | Synovus Financial Corp | Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E        
Business Combination [Line Items]        
Business Combination, Conversion Ratio | shares 1      
Legacy Pinnacle        
Business Combination [Line Items]        
Common stock, par value (in dollars per share) | $ / shares $ 1.00      
Conversion ratio (in shares) | shares 1      
Legacy Pinnacle | Fixed-Rate Non-Cumulative Perpetual Preferred Stock, Series C        
Business Combination [Line Items]        
Preferred stock, dividend rate 6.75%      
Legacy Pinnacle | Synovus Financial Corp | Fixed-Rate Non-Cumulative Perpetual Preferred Stock, Series C        
Business Combination [Line Items]        
Business Combination, Conversion Ratio | shares 1      
Legacy Pinnacle | Synovus Financial Corp | Preferred Stock        
Business Combination [Line Items]        
Equity interest per share 0.025      
Newco | Fixed-Rate Non-Cumulative Perpetual Preferred Stock, Series C        
Business Combination [Line Items]        
Preferred stock, dividend rate 6.75%