Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)

v3.8.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)
 12 Months Ended 58 Months Ended
Dec. 31, 2005
acquisition
Dec. 31, 2017
USD ($)
ATM
branch
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Number of bank branches | branch   111    
Number of ATMs | ATM   180    
Number of business acquisitions | acquisition 2      
Held for trading securities   $ 0    
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%  
Number of Days Past Due to Charge Off Real Estate Secured Loans   180 days    
Future payments, contractual term   6 months    
Goodwill   $ 298,528,000 $ 298,191,000 $ 298,191,000
Impairment charges for goodwill or intangible assets   0    
Liabilities for post retirement benefits payable to other beneficiaries   6,300,000 5,900,000 5,900,000
Affordable housing projects, recognized amortization   1,300,000 370,000  
Affordable housing projects, tax credits   858,000 882,000  
Affordable housing projects, investment amount   11,000,000 9,900,000 9,900,000
Affordable housing projects, liability   $ 7,300,000 $ 7,100,000 $ 7,100,000
Stock options granted | shares   0 0 0
Accruals for uncertain tax positions   $ 0 $ 0 $ 0
Minimum        
Commercial loans on nonaccrual status, period   90 days    
Period of independent appraisal or valuation   12 months    
Period past due to change TDR status   30 days    
Estimated useful life of bank premises   3 years    
Percentage of fair value of the derivative instruments for the hedge to be highly effective   80.00%    
Interest rate lock commitments period   30 days    
Tax Position Benefit Recognition Threshold   50.00%    
Maximum        
Period past due to charge off consumer loans non-real estate secured   120 days    
Estimated useful life of bank premises   50 years    
Percentage of fair value of the derivative instruments for the hedge to be highly effective   125.00%    
Interest rate lock commitments period   120 days    
Core Deposits | Minimum        
Intangible assets, amortization period   4 years    
Core Deposits | Maximum        
Intangible assets, amortization period   14 years