INCOME TAXES - Schedule of Effective Income Tax Rate (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount:                      
Provision at expected rate                 $ 5,804 $ 5,996 $ 6,260
(Decrease) increase in tax resulting from                      
Tax-exempt income                 (1,092) (1,492) (1,673)
Tax credits                 (312) (737) (737)
Other, net                 197 (31) (46)
Total provision $ 1,290 $ 1,273 $ 1,152 $ 882 $ 1,106 $ 957 $ 825 $ 848 $ 4,597 $ 3,736 $ 3,804
Effective Income Tax Rate Reconciliation, Percent:                      
Provision at expected rate (as a percent)                 34.00% 34.00% 34.00%
(Decrease) increase in tax resulting from:                      
Tax-exempt income (as a percent)                 (6.40%) (8.46%) (9.09%)
Tax credits (as a percent)                 (1.83%) (4.17%) (4.00%)
Other, net (as a percent)                 1.16% (0.18%) (0.25%)
Effective income tax provision (benefit) and rate (as a percent)                 26.93% 21.19% 20.66%