Quarterly report pursuant to Section 13 or 15(d)

ACCOUNTING POLICIES (Narrative) (Details)

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ACCOUNTING POLICIES (Narrative) (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Apr. 30, 2019
USD ($)
Feb. 01, 2019
USD ($)
shares
Mar. 31, 2020
USD ($)
item
Mar. 31, 2019
USD ($)
Dec. 31, 2019
USD ($)
Accounting Policies [Line Items]          
Number of bank branches | item     149    
Number of ATM's | item     170    
Impairment charges for goodwill $ 0   $ 0    
Goodwill     935,560   $ 935,560
Loans held for investment, accrued interest receivable     31,100    
HTM securities, Accrued interest receivable     5,200    
Cash paid in acquisition     $ 0 $ 12  
Federal Home Loan Bank requires Bank to maintain percentage of stock equal to outstanding borrowings     4.25%   4.25%
Percentage of Federal Reserve Bank of Richmond reserve     6.00%   6.00%
Minimum          
Accounting Policies [Line Items]          
Intangible assets, amortization period (years)     4 years    
Maximum          
Accounting Policies [Line Items]          
Intangible assets, amortization period (years)     10 years    
Access National Bank          
Accounting Policies [Line Items]          
Number of shares equivalent to each share of acquired entity | shares   0.75      
Company's common shares issued | shares   15,842,026      
Cash paid in acquisition   $ 12