Quarterly report pursuant to Section 13 or 15(d)

SECURITIES (Narrative) (Details)

v3.7.0.1
SECURITIES (Narrative) (Details)
 3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
security
Jun. 30, 2015
USD ($)
Dec. 31, 2016
USD ($)
security
Dec. 31, 2015
USD ($)
Schedule of Investments [Line Items]        
Individual securities that had been in a continuous loss position for more than 12 months, amount $ 79,042,000   $ 83,152,000  
Securities that had been in a continuous loss position for more than 12 months, unrealized loss 1,098,000   1,790,000  
Held to maturity securities unrealized gains before tax 4,800,000 $ 8,100,000 5,200,000  
Held-to-maturity securities in continuous loss position for more than 12 months $ 648,000   $ 648,000  
Number of held-to-maturity securities in unrealized loss positions | security 1   1  
Held-to-maturity securities, continuous unrealized loss position, more than 12 months $ 32,000   $ 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 37,800,000   $ 37,000,000  
Credit-related OTTI $ 0     $ 300,000
Available-for-sale Securities        
Schedule of Investments [Line Items]        
Individual securities that had been in a continuous loss position | security 30   30