v3.25.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Apr. 30, 2024
Dec. 31, 2023
Summary Of Significant Accounting Policies [Line Items]          
Net increase to retained earnings $ 430,267,000   $ 423,552,000    
Reduction to allowance for credit losses $ (75,150,000) $ (66,251,000) (72,992,000)   $ (65,888,000)
Federal funds sales periods 1 day        
Interest-earning deposits maturities period 1 year        
Servicing rights $ 0        
Amount of loans serviced 141,600,000   139,400,000    
Loans held for sale $ 8,700,000   9,300,000    
Threshold period for loan 30 days        
Threshold for determining nonaccrual status 90 days        
Stock options granted 0        
Unrecognized compensation cost $ 0        
Issuance of shares for Employee Stock Purchase Plan, shares 7,115 11,145      
Antidilutive securities 20,885 191,016      
Phantom Plan          
Summary Of Significant Accounting Policies [Line Items]          
Stock options granted 145,058        
2024 ESPP          
Summary Of Significant Accounting Policies [Line Items]          
Number of share purchase rights authorized       150,000  
Restricted stock [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Shares granted 88,101        
Compensation cost $ 3,300,000 $ 2,700,000      
Restricted stock [Member] | Tranche One [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Stock option vesting term 3 years        
Restricted stock [Member] | Tranche Two [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Stock option vesting term 5 years        
Performance Shares [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Shares granted 66,252        
Performance Shares [Member] | 2021 Long-Term Stock Incentive Plan          
Summary Of Significant Accounting Policies [Line Items]          
Shares granted 66,252        
Restricted Stock Units [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Unrecognized compensation cost $ 9,000,000        
Weighted average period over which unrecognized compensation is expected to be recognized (in years) 2 years 2 months 26 days        
Restricted Stock Units [Member] | 2021 Long-Term Stock Incentive Plan          
Summary Of Significant Accounting Policies [Line Items]          
Shares granted 88,101        
Employee Stock [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Compensation cost $ 39,000 32,000      
Percentage of closing market price on purchase date 85.00%        
Phantom Units          
Summary Of Significant Accounting Policies [Line Items]          
Unrecognized compensation cost $ 11,000,000        
Consumer and Other [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Reduction to allowance for credit losses $ (2,574,000) $ (915,000) $ (1,184,000)   $ (869,000)
Consumer and Other [Member] | Closed-end Loans [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Threshold for determining nonaccrual status 120 days        
Consumer and Other [Member] | Open-end Loans [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Threshold for determining nonaccrual status 180 days        
Maximum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Cash equivalents original maturities period 90 days        
Short term borrowings original maturities period 90 days        
Finite-Lived Intangible Asset, Useful Life 15 years        
Maximum [Member] | Employee Stock Option [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Option term 10 years        
Maximum [Member] | Employee Stock [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of compensation contributable 15.00%        
Minimum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Finite-Lived Intangible Asset, Useful Life 5 years        
Minimum [Member] | Employee Stock [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of compensation contributable 1.00%        
Peapack-Gladstone Mortgage Group, Inc. [Member] | Peapack Ventures, LLC [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of interest owned 99.00%        
Peapack-Gladstone Mortgage Group, Inc. [Member] | Peapack-Gladstone Realty, Inc [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of interest owned 79.00%        
PGB Trust & Investments of Delaware [Member] | Peapack Ventures, LLC [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of interest owned 1.00%        
Peapack Ventures, LLC [Member] | Peapack-Gladstone Realty, Inc [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of interest owned 21.00%