Annual report pursuant to Section 13 and 15(d)

SECURITIES (Narrative) (Details)

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SECURITIES (Narrative) (Details)
 3 Months Ended 12 Months Ended
Jun. 30, 2015
USD ($)
Dec. 31, 2017
USD ($)
security
Dec. 31, 2016
USD ($)
security
Dec. 31, 2015
USD ($)
Schedule of Investments [Line Items]        
Available for sale securities that had been in a continuous loss position for more than 12 months, amount   $ 197,640,000 $ 83,152,000  
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss   4,188,000 1,790,000  
Held to maturity securities unrealized gains before tax $ 8,100,000 3,600,000 5,200,000  
Held-to-maturity securities in a continuous loss position for longer than 12 months, fair value   $ 1,100,000 $ 648,000  
Held-to-maturity securities in a continuous loss position for longer than 12 months, number of securities | security   2 1  
Held to maturity securities in a continuous loss position, more than 12 months, accumulated loss   $ 31,000 $ 81,000  
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%  
Restricted equity securities consist of Federal Reserve Bank stock   $ 27,600,000 $ 23,800,000  
Federal Home Loan Bank Stock   47,700,000 $ 37,000,000  
Credit-related OTTI   $ 0   $ 300,000
Available-for-sale Securities        
Schedule of Investments [Line Items]        
Available for sale securities that had been in a continuous loss position | security   71 30